ABSTRACT
To survive and pass on their genes, animals must perform many tasks that affect their fitness, such as mate-choice, foraging, and predator avoidance. The ability to make rapid decisions is dependent on the information that needs to be sampled from the environment and how it is processed. We highlight the need to consider visual attention within sensory ecology and advocate the use of eye-tracking methods to better understand how animals prioritise the sampling of information from their environments prior to making a goal-directed decision. We consider ways in which eye-tracking can be used to determine how animals work within attentional constraints and how environmental pressures may exploit these limitations.
Subject(s)
Eye Movements , Visual Perception , Animals , Attention , EcologyABSTRACT
BACKGROUND: It has been hypothesised that abnormal functioning of the mirror neuron system (MNS) may lead to deficits in imitation and the internal representation of movement, potentially contributing to the motor impairments associated with developmental coordination disorder (DCD). AIMS: Using fMRI, this study examined brain activation patterns in children with and without DCD on a finger adduction/abduction task during four MNS activation states: observation; motor imagery; execution; and imitation. METHODS AND PROCEDURES: Nineteen boys (8.25-12.75 years) participated, including 10 children with DCD (≤16th percentile on MABC-2; no ADHD/ASD), and nine typically developing controls (≥25th percentile on MABC-2). OUTCOMES AND RESULTS: Even though children with DCD displayed deficits behaviourally on imitation (Sensory Integration & Praxis Test Subtests) and motor imagery assessments prior to scanning, no differences in MNS activation were seen between the DCD and control groups at a neurological level, with both groups activating mirror regions effectively across conditions. Small clusters of decreased activation during imitation were identified in non-mirror regions in the DCD group, including the thalamus, caudate, and posterior cingulate - regions involved in motor planning and attentional processes. CONCLUSIONS AND IMPLICATIONS: The results of this study do not provide support for the MNS dysfunction theory as a possible causal mechanism for DCD. Further research to explore attentional and motor planning processes and how they may interact at a network level may enhance our understanding of this complex disorder.
Subject(s)
Brain/diagnostic imaging , Mirror Neurons/physiology , Motor Skills Disorders/diagnostic imaging , Brain/physiopathology , Case-Control Studies , Child , Fingers , Functional Neuroimaging , Humans , Imagination , Imitative Behavior , Magnetic Resonance Imaging , Male , Motor Skills Disorders/physiopathology , Reproducibility of ResultsABSTRACT
Stable trimeric forms of human immunodeficiency virus recombinant gp140 (rgp140) are important templates for determining the structure of the glycoprotein to assist in our understanding of HIV infection and host immune response. Such information will aid the design of therapeutic drugs and vaccines. Here, we report the production of a highly stable and trimeric rgp140 derived from a HIV type 1 (HIV-1) subtype D isolate that may be suitable for structural studies. The rgp140 is functional in terms of binding to CD4 and three human monoclonal antibodies (17b, b12, and 2G12) that have broad neutralizing activities against a range of HIV-1 isolates from different subtypes. Treatment of rgp140 with protein disulfide isomerase (PDI) severely restricted 17b binding capabilities. The stable nature of the rgp140 was due to the lack of processing at the gp120/41 boundary and the presence of an intermonomer disulfide bond formed by the cysteines of the V3 loop. Further characterization showed the intermonomer disulfide bond to be a target for PDI processing. The relevance of these findings to the roles of the V3 domain and the timing of PDI action during the HIV infection process are discussed.
Subject(s)
Disulfides/metabolism , Gene Products, env/chemistry , HIV-1/chemistry , Protein Binding , Protein Conformation , Protein Disulfide-Isomerases/metabolism , Animals , Antibodies, Monoclonal/metabolism , Blotting, Western , CHO Cells , Cricetinae , Cricetulus , DNA Primers , Dimerization , Gene Products, env/genetics , Sequence Analysis, DNA , env Gene Products, Human Immunodeficiency VirusABSTRACT
The human complement regulator CD55 is a key molecule protecting self-cells from complement-mediated lysis. X-ray diffraction and analytical ultracentrifugation data reveal a rod-like arrangement of four short consensus repeat (SCR) domains in both the crystal and solution. The stalk linking the four SCR domains to the glycosylphosphatidylinositol anchor is extended by the addition of 11 highly charged O-glycans and positions the domains an estimated 177 A above the membrane. Mutation mapping and hydrophobic potential analysis suggest that the interaction with the convertase, and thus complement regulation, depends on the burial of a hydrophobic patch centered on the linker between SCR domains 2 and 3.
Subject(s)
CD55 Antigens/chemistry , Complement System Proteins/physiology , Crystallization , Glycosylation , Humans , Hydrophobic and Hydrophilic Interactions , Models, Molecular , Repetitive Sequences, Amino Acid , Solutions , von Willebrand Factor/chemistryABSTRACT
Conversion of the aflatoxin biosynthetic intermediate versiconal hemiacetal acetate (VHA) in a cell free extract of Aspergillus parasiticus ATCC 15517 is investigated. The enzymatic reaction is monitored by a method using high performance liquid chromatography (HPLC). The major product of the enzymatic reaction is a water soluble compound not chloroform-extractable at pH 7.5. The product becomes chloroform extractable upon acidification of the reaction medium and is separated and quantitated by reversed-phase HPLC. It is tentatively identified as 'versiconal hemiacetal alcohol,' which is converted to versicolorin C (VC) upon acid treatment.
