90 research outputs found
Rhesus Monkeys See Who They Hear: Spontaneous Cross-Modal Memory for Familiar Conspecifics
Rhesus monkeys gather much of their knowledge of the social world through visual input and may preferentially represent this knowledge in the visual modality. Recognition of familiar faces is clearly advantageous, and the flexibility and utility of primate social memory would be greatly enhanced if visual memories could be accessed cross-modally either by visual or auditory stimulation. Such cross-modal access to visual memory would facilitate flexible retrieval of the knowledge necessary for adaptive social behavior. We tested whether rhesus monkeys have cross-modal access to visual memory for familiar conspecifics using a delayed matching-to-sample procedure. Monkeys learned visual matching of video clips of familiar individuals to photographs of those individuals, and generalized performance to novel videos. In crossmodal probe trials, coo-calls were played during the memory interval. The calls were either from the monkey just seen in the sample video clip or from a different familiar monkey. Even though the monkeys were trained exclusively in visual matching, the calls influenced choice by causing an increase in the proportion of errors to the picture of the monkey whose voice was heard on incongruent trials. This result demonstrates spontaneous cross-modal recognition. It also shows that viewing videos of familiar monkeys activates naturally formed memories of real monkeys, validating the use of video stimuli in studies of social cognition in monkeys
Off-the-Shelf Gd(NO3)(3) as an Efficient High-Spin Metal Ion Polarizing Agent for Magic Angle Spinning Dynamic Nuclear Polarization
[Image: see text] Magic angle spinning nuclear magnetic resonance spectroscopy experiments are widely employed in the characterization of solid media. The approach is incredibly versatile but deleteriously suffers from low sensitivity, which may be alleviated by adopting dynamic nuclear polarization methods, resulting in large signal enhancements. Paramagnetic metal ions such as Gd(3+) have recently shown promising results as polarizing agents for (1)H, (13)C, and (15)N nuclear spins. We demonstrate that the widely available and inexpensive chemical agent Gd(NO(3))(3) achieves significant signal enhancements for the (13)C and (15)N nuclear sites of [2-(13)C,(15)N]glycine at 9.4 T and ∼105 K. Analysis of the signal enhancement profiles at two magnetic fields, in conjunction with electron paramagnetic resonance data, reveals the solid effect to be the dominant signal enhancement mechanism. The signal amplification obtained paves the way for efficient dynamic nuclear polarization without the need for challenging synthesis of Gd(3+) polarizing agents
The potential to encode sex, age, and individual identity in the alarm calls of three species of Marmotinae
In addition to encoding referential information and information about the sender’s motivation, mammalian alarm calls may encode information about other attributes of the sender, providing the potential for recognition among kin, mates, and neighbors. Here, we examined 96 speckled ground squirrels (Spermophilus suslicus), 100 yellow ground squirrels (Spermophilus fulvus) and 85 yellow-bellied marmots (Marmota flaviventris) to determine whether their alarm calls differed between species in their ability to encode information about the caller’s sex, age, and identity. Alarm calls were elicited by approaching individually identified animals in live-traps. We assume this experimental design modeled a naturally occurring predatory event, when receivers should acquire information about attributes of a caller from a single bout of alarm calls. In each species, variation that allows identification of the caller’s identity was greater than variation allowing identification of age or sex. We discuss these results in relation to each species’ biology and sociality
Macrocycle Conformational Sampling with MacroModel
Sampling low energy conformations
of macrocycles is challenging
due to the large size of many of these molecules and the constraints
imposed by the macrocycle. We present a new conformational search
method (implemented in MacroModel) that uses brief MD simulations
followed by minimization and normal-mode search steps. The method
was parametrized using a set of 100 macrocycles from the PDB and CSD.
It was then tested on a publicly available data set for which there
are published results using alternative methods; we found that when
the same force field is used (in this case MMFFs in vacuum), our method
tended to identify conformations with lower energies than what the
other methods identified. The performance on a new set of 50 macrocycles
from the PDB and CSD was also quite good; the mean and median RMSD
values for just the ring atoms were 0.60 and 0.33 Ã…, respectively.
However, the RMSD values for macrocycles with more than 30 ring-atoms
were quite a bit larger compared to the smaller macrocycles. Possible
origins for this and ideas for improving the performance on very large
macrocycles are discussed
Recommended from our members
MRI surveillance following treatment of extremity soft tissue sarcoma
Background and Objectives
Local recurrence (LR) following limb-sparing surgery and radiation therapy (RT) for extremity soft tissue sarcoma (STS) is rare. The current study investigates the utility of surveillance nuclear magnetic resonance imaging (MRI) for detection of asymptomatic LRs.
Methods
The study cohort consisted of 168 adult patients with extremity STS treated with limb-sparing surgery and RT with curative intent between October 2001 and January 2011. Follow-up surveillance MRIs and history and physical examinations were performed per the NCCN guidelines with additional MRIs as clinically indicated. The method of LR detection and MRI number and indication were determined.
Results
After a median follow-up of 4.7 years (range: 0.6-10.5) 11 (6.5%; 11/168) patients developed LRs. Five hundred two MRIs were obtained, 429 (85.5%; 429/502) for surveillance and 73 (14.5%; 73/502) as clinically indicated. One hundred fourteen patients underwent >= 1 surveillance MRI. The median surveillance MRI interval was 6.4 months (range 1.4-68.9). Surveillance MRI detected an asymptomatic LR in 1 (0.9%; 1/114) patient with a complex reconstruction.
Conclusions
Surveillance MRI infrequently detects asymptomatic LRs following limb-sparing surgery and RT for extremity STS and should be limited to patients whose primary tumor sites are not easily assessed by history and physical examination. J. Surg. Oncol. 2014 109:???-???. (c) 2013 Wiley Periodicals, Inc
The genome of the obligate intracellular parasite Trachipleistophora hominis : new insights into microsporidian genome dynamics and reductive evolution
The dynamics of reductive genome evolution for eukaryotes living inside other eukaryotic cells are poorly understood compared to well-studied model systems involving obligate intracellular bacteria. Here we present 8.5 Mb of sequence from the genome of the microsporidian Trachipleistophora hominis, isolated from an HIV/AIDS patient, which is an outgroup to the smaller compacted-genome species that primarily inform ideas of evolutionary mode for these enormously successful obligate intracellular parasites. Our data provide detailed information on the gene content, genome architecture and intergenic regions of a larger microsporidian genome, while comparative analyses allowed us to infer genomic features and metabolism of the common ancestor of the species investigated. Gene length reduction and massive loss of metabolic capacity in the common ancestor was accompanied by the evolution of novel microsporidian-specific protein families, whose conservation among microsporidians, against a background of reductive evolution, suggests they may have important functions in their parasitic lifestyle. The ancestor had already lost many metabolic pathways but retained glycolysis and the pentose phosphate pathway to provide cytosolic ATP and reduced coenzymes, and it had a minimal mitochondrion (mitosome) making Fe-S clusters but not ATP. It possessed bacterial-like nucleotide transport proteins as a key innovation for stealing host-generated ATP, the machinery for RNAi, key elements of the early secretory pathway, canonical eukaryotic as well as microsporidian-specific regulatory elements, a diversity of repetitive and transposable elements, and relatively low average gene density. Microsporidian genome evolution thus appears to have proceeded in at least two major steps: an ancestral remodelling of the proteome upon transition to intracellular parasitism that involved reduction but also selective expansion, followed by a secondary compaction of genome architecture in some, but not all, lineages.Publisher PDFPeer reviewe
- …