Berkelium is positioned at a crucial location in the actinide series between the inherently stable half-filled 5f(7) configuration of curium and the abrupt transition in chemical behavior created by the onset of a metastable divalent state that starts at californium. However, the mere 320-day half-life of berkelium's only available isotope, (249)Bk, has hindered in-depth studies of the element's coordination chemistry. Herein, we report the synthesis and detailed solid-state and solution-phase characterization of a berkelium coordination complex, Bk(III)tris(dipicolinate), as well as a chemically distinct Bk(III) borate material for comparison. We demonstrate that berkelium's complexation is analogous to that of californium. However, from a range of spectroscopic techniques and quantum mechanical calculations, it is clear that spin-orbit coupling contributes significantly to berkelium's multiconfigurational ground state.

Somatotopic organization was demonstrated by means of microelectrode mapping studies of three somatic sensory nuclear regions in the raccoon medulla.Projections of peripheral receptive fields in the cuneate-gracile nuclear complex occur iteratively in rostro-caudal columns. These projections are organized into a detailed 3-dimensional pattern, in contrast to the more diffuse intermingling of such projections in the spinal dorsal roots and columns. 'This indicates that afferent fibers are re-sorted before synaptic termination. In the extensive representation of the volar hand, there are distinct subnuclei, delineated by intervening fiber laminae, each containing the projections from one of the forepaw digits.Units in the external-cuneate nucleus responded only to stimulation of deeperlying tissues in anterior body regions. These projections were also somatotopically organized. Retrograde degeneration studies indicated that some cells, in that region where cuneate-gracile adjoins external-cuneate, may project through both the ipsilatera1 cerebellar peduncles and the contralateral midbrain.( 3 ) The spinal trigeminal nucleus adjoining the cuneate-gracile complex displayed many characteristics similar to those of the latter.Neighboring, although anatomically distinct, regions contained projections from neighboring peripheral receptive fields.( 1) ( )The raccoon's propensity to palpate and and manipulate objects and surfaces with its hands has prompted a series of investigations of the somatic sensory system in these animals. A pronounced differential enlargement of cellular populations which are activated by light mechanical stimulation of each of the hand digits was found at both the cerebral neocortical and thalamic levels of this afferent system (Welker and Seidenstein, '59; Welker and Johnson, ' 6 5 ) . The relatively large development of these digital representations was found to be associated at both cortex and thalamus with certain morphological specializations. Thus, the individuated digital representations were projected: at the cortex into adjacent gyri separated by sulci, and within the thalamus into adjacent subnuclei separated by fibrous laminae.The purpose of the present study was to determine whether a similar degree of differentiation, and of correlation between somatotopic organization and nuclear morphology, also exists in the dorsal column nuclei which contain synapses of the first order somatic sensory afferents from the body. By means of the combined use of J. COMP. NEUR., 132: 1-44. microelectrode mapping and neuroanatomical methods it was found that such a correlation does exist. Our results also emphasize the importance of determining the exact peripheral locus of mechanoreceptors that activate each of the many subnuclei which constitute the three-dimensional cellular mosaic of the cuneategracile nuclear complex. SubjectsEighteen adult raccoons (Procyon Zotor) were used in electrophysiological recording, four in retrograde degeneration, and three in normal histological studies. El...

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Ceratocystis fimbriata is a widely distributed, plant pathogenic fungus that causes wilts and cankers on many woody hosts. Earlier phylogenetic analyses of DNA sequences revealed three geographic clades within the C. fimbriata complex that are centered respectively in North America, Latin America and Asia. This study looked for cryptic species within the North American clade. The internal transcribed spacer regions (ITS) of the rDNA were sequenced, and phylogenetic analysis indicated that most isolates from the North American clade group into four host-associated lineages, referred to as the aspen, hickory, oak and cherry lineages, which were isolated primarily from wounds or diseased trees of Populus, Carya, Quercus and Prunus, respectively. A single isolate collected from P. serotina in Wisconsin had a unique ITS sequence. Allozyme electromorphs also were highly polymorphic within the North American clade, and the inferred phylogenies from these data were congruent with the ITS-rDNA analyses. In pairing experiments isolates from the aspen, hickory, oak and cherry lineages were interfertile only with other isolates from their respective lineages. Inoculation experiments with isolates of the four host-associated groupings showed strong host specialization by isolates from the aspen and hickory lineages on Populus tremuloides and Carya illinoensis, respectively, but isolates from the oak and cherry lineages did not consistently reveal host specialization. Morphological features distinguish isolates in the North American clade from those of the Latin American clade (including C. fimbriata sensu stricto). Based on the phylogenetic evidence, interfertility, host specialization and morphology, the oak and cherry lineages are recognized as the earlier described C. variospora, the poplar lineage as C. populicola sp. nov., and the hickory lineage as C. caryae sp. nov. A new species associated with the bark beetle Scolytus quadrispinosus on Carya is closely related to C. caryae and is described as C. smalleyi.

Cetacean (dolphin, whale, and porpoise) brains are among the least studied mammalian brains because of the formidability of collecting and histologically preparing such relatively rare and large specimens. Magnetic resonance imaging offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Furthermore, internal structures can be analyzed in their precise anatomic positions, which is difficult to accomplish after the spatial distortions often accompanying histological processing. In this study, images of the brain of an adult bottlenose dolphin, Tursiops truncatus, were scanned in the coronal plane at 148 antero-posterior levels. From these scans a computer-generated three-dimensional model was constructed using the programs VoxelView and VoxelMath (Vital Images, Inc.). This model, wherein details of internal and external morphology are represented in three-dimensional space, was then resectioned in orthogonal planes to produce corresponding series of virtual sections in the horizontal and sagittal planes. Sections in all three planes display the sizes and positions of major neuroanatomical features such as the arrangement of cortical lobes and subcortical structures such as the inferior and superior colliculi, and demonstrate the utility of MRI for neuroanatomical investigations of dolphin brains. Anat Rec 264: [397][398][399][400][401][402][403][404][405][406][407][408][409][410][411][412][413][414] 2001.