23684652
Comparison of electrical thresholds for evoking movements from sensori-motor areas of the cat cerebral cortex and its relation to motor training
Motor maps and electrical thresholds for evoking movements from motor areas of the cerebral cortex were evaluated in normal cats by using intracortical microstimulation techniques. Stainless steel chambers were implanted over craniotomies in adult cats trained to perform reaching and retrieval movements with their forelimbs. Prehensile motor training was continued and movement performance monitored for about 6–10 weeks during which the cortex was progressively explored with sharp tungsten electrodes inserted into cortical gyri (anterior and posterior sigmoid, and coronal) and the banks of sulci (cruciate, presylvian and coronal). Twice weekly, under light general anaesthesia, 3–4 tracks were made in either hemisphere till about 50 tracks were made in each hemisphere. Mean thresholds for evoking forelimb movements from different cytoarchitectonic areas (4γ, 4δ, 6aγ and 3a) were compared and no consistent or significant differences were observed between the different areas. In the animals (4/6) which used either forelimb to perform the tasks, there were no consistent differences in the mean thresholds for evoking forelimb movements from the two hemispheres. However, in 2 animals, which used their right forelimbs predominantly or exclusively to perform all the tasks, mean thresholds for evoking forelimb movements was significantly higher in areas 4γ and 6aγ of the left hemisphere (compared to the right); no consistent differences in the mean thresholds for evoking hindlimb or facial movements were observed between the two hemispheres. These findings suggest that ICMS thresholds for evoking forelimb movements may be similar in different sensorimotor areas of the cat cerebral cortex, and these thresholds could be influenced by motor training.
27083545
Ipsilateral cortical connections of area 6 in the cat cerebral cortex.
Many motor areas have been identified within cytoarchitectonic area 6 of the cerebral cortex in primates. To provide a better understanding of the motor functions of area 6 in the cat, the ipsilateral cortical connections of the different cytoarchitectonic subdivisions of area 6 (areas 6a alpha, 6a beta, 6a gamma, and 6iffu) were studied by the use of fluorescent retrograde tracers. Tracer injections, made in the forelimb and face regions of areas 6a alpha and 6a gamma, were guided by data from intracortical microstimulation (ICMS). ICMS did not evoke movements from areas 6a beta and 6iffu. Retrogradely labeled neurons were enumerated in cytoarchitectonically identified areas in the frontal and parietal lobes to show that the subdivisions of area 6 are strongly interconnected except for areas 6a gamma and 6a beta. There are considerable differences in the pattern of connections of the area 6 subdivisions with area 4 and with prefrontal, cingulate, and parietal cortices. Area 4 gamma projects strongly to area 6a gamma but not to the other subdivisions. Areas 4 delta, 4fu, and 4sfu project strongly to 6a alpha and 6iffu but relatively weakly to area 6a beta. Prefrontal areas project strongly to area 6a beta and 6iffu, moderately to 6a alpha, but weakly to area 6a gamma. Cingulate areas project strongly to area 6iffu and moderately to areas 6a alpha and 6a beta but do not project to area 6a gamma. Parietal projections from primary and second somatosensory cortex were directed to area 6a gamma, whereas areas 5, 7, and insula were found to project to all the subdivisions of area 6. These findings support earlier suggestions that secondary motor areas may be located in areas 6a alpha and 6a gamma (Ghosh [1997] J. Comp. Neurol. 380:191-214). Features of the pattern of cortical connections of area 6 common to the cat and primates suggest that their motor areas in the frontal lobe are organized in a similar manner.
37405816
Cytoarchitecture of sensorimotor areas in the cat cerebral cortex.
The organization of multiple motor areas in the cerebral cortex has been investigated frequently in primates but rarely in nonprimate species. To compare sensorimotor areas in cats and primates, the cytoarchitecture of frontal and parietal areas of the cat cerebral cortex was described and mapped from coronal sections stained with cresyl violet or thionine. Multiple subdivisions of areas 4 and 6 were recognized; of these, the cytoarchitecture of area 4 gamma is similar to that of area 4 described in other carnivores and in primates and is characterized by giant pyramidal cells in multiple rows or clusters in lamina V. In other subdivisions of area 4 (4 delta, 4sfu, and 4fu), giant pyramidal cells are few or absent in lamina V, and these subdivisions resemble area 6 of primates. Area 6 of the cat cortex is heterogeneous, and differences in laminar appearance and size of pyramidal cells in lamina V distinguish its four subdivisions (6a alpha, 6a beta, 6a gamma, and 6iffu). The adjoining prefrontal areas are distinguishable from area 6 by the presence of a thin internal granular lamina (lamina IV) and the reduced size of pyramidal cells in lamina V. Laminae are poorly differentiated in the cingulate areas, where a rostral and caudal subdivision can be distinguished on the basis of the absence or presence of lamina IV. Area 3a is characterized by a thin lamina IV and is located between frontal agranular and parietal granular (well-defined lamina IV) fields (3b, 1, 2, 2pri, 5, and 7). Insular cortex can be subdivided into granular and agranular fields.
12219567
Application of rbcL based molecular diversity analysis to algae in wastewater treatment plants.
The molecular diversity of algae in the final clarifier or denitrification filter outfall from three wastewater treatment plants (WWTPs) with activated sludge based treatment was analyzed using the rbcL gene as a phylogenetic marker. The rbcL gene encodes the large subunit of the CO(2) fixing enzyme RuBisCO. Among algae identified at the WWTPs were diatoms, green algae, cyanobacteria, Eustigmatophyceae, and unknown heterokonts. A high level of diversity was observed within WWTPs with 19-24 unique rbcL sequences detected at each plant. Algae composition also varied between treatment plants. Our results show that the rbcL gene can be used as a phylogenetic marker for algae diversity analysis in a wastewater treatment context.
33844160
Detection of a large number of subgroup 1 human rotaviruses with a “long” RNA electropherotype
SummaryThe long or short electrophoretic migration patterns of group A human rotaviruses are linked to their subgroup antigenic specificities. Long pattern isolates usually belong to subgroup 2 (SG2) and short pattern to subgroup 1 (SG1). To date detection of only 4 isolates which do not follow this linkage, have been reported. In the present communication we report the detection of unusually large number (39 isolates) of long pattern human isolates with SG1 specificities.
11257195
A quantile-based method for association mapping of quantitative phenotypes: an application to rheumatoid arthritis phenotypes
Genetic association of population-based quantitative trait data has traditionally been analyzed using analysis of variance (ANOVA). However, violations of certain statistical assumptions may lead to false-positive association results. In this study, we have explored model-free alternatives to ANOVA using correlations between allele frequencies in the different quantile intervals of the quantitative trait and the quantile values. We performed genome-wide association scans on anti-cyclic citrullinated peptide and rheumatoid factor-immunoglobulin M, two quantitative traits correlated with rheumatoid arthritis, using the data provided in Genetic Analysis Workshop 16. Both the quantitative traits exhibited significant evidence of association on Chromosome 6, although not in the human leukocyte antigen region which is known to harbor a major gene predisposing to rheumatoid arthritis. We found that while a majority of the significant findings using the asymptotic thresholds of ANOVA was not validated using permutations, a relatively higher proportion of the significant findings using the asymptotic cut-offs of the correlation statistic were validated using permutations.
25523214
Dissecting the correlation structure of a bivariate phenotype: Common genes or shared environment?
High correlations between two quantitative traits may be either due to common genetic factors or common environmental factors or a combination of both. In this study, we develop statistical methods to extract the genetic contribution to the total correlation between the components of a bivariate phenotype. Using data on bivariate phenotypes and marker genotypes for sib-pairs, we propose a test for linkage between a common QTL and a marker locus based on the conditional cross-sib trait correlations (trait 1 of sib 1—trait 2 of sib 2 and conversely) given the identity-by-descent (i.b.d.) sharing at the marker locus. We use Monte-Carlo simulations to evaluate the performance of the proposed test under different trait parameters and quantitative trait distributions. An application of the method is illustrated using data on two alcohol-related phenotypes from a project on the collaborative study on the genetics of alcoholism.
207128360
Spectroscopic and electronic structure studies of phenolate Cu(II) complexes: phenolate ring orientation and activation related to cofactor biogenesis.
A combination of spectroscopies and DFT calculations have been used to define the electronic structures of two crystallographically defined Cu(II)-phenolate complexes. These complexes differ in the orientation of the phenolate ring which results in different bonding interactions of the phenolate donor orbitals with the Cu(II), which are reflected in the very different spectroscopic properties of the two complexes. These differences in electronic structures lead to significant differences in DFT calculated reactivities with oxygen. These calculations suggest that oxygen activation via a Cu(I) phenoxyl ligand-to-metal charge transfer complex is highly endergonic (>50 kcal/mol), hence an unlikely pathway. Rather, the two-electron oxidation of the phenolate forming a bridging Cu(II) peroxoquinone complex is more favorable (11.3 kcal/mol). The role of the oxidized metal in mediating this two-electron oxidation of the coordinated phenolate and its relevance to the biogenesis of the covalently bound topa quinone in amine oxidase are discussed.