Selection on bristle length has the ability to drive the evolution of male abdominal appendages in the sepsid fly Themira biloba.

Many exaggerated and novel traits are strongly influenced by sexual selection. Although sexual selection is a powerful evolutionary force, underlying genetic interactions can constrain evolutionary outcomes. The relative strength of selection vs. constraint has been a matter of debate for the evolution of male abdominal appendages in sepsid flies. These abdominal appendages are involved in courtship and mating, but their function has not been directly tested. We performed mate choice experiments to determine whether sexual selection acts on abdominal appendages in the sepsid Themira biloba. We tested whether appendage bristle length influenced successful insemination by surgically trimming the bristles. Females paired with males that had shortened bristles laid only unfertilized eggs, indicating that long bristles are necessary for successful insemination. We also tested whether the evolution of bristle length was constrained by phenotypic correlations with other traits. Analyses of phenotypic covariation indicated that bristle length was highly correlated with other abdominal appendage traits, but was not correlated with abdominal sternite size. Thus, abdominal appendages are not exaggerated traits like many sexual ornaments, but vary independently from body size. At the same time, strong correlations between bristle length and appendage length suggest that selection on bristle length is likely to result in a correlated increase in appendage length. Bristle length is under sexual selection in T. biloba and has the potential to evolve independently from abdomen size.

Magnetic resonance images of the brain of a dwarf sperm whale (Kogia simus).

Cetacean (dolphin, whale and porpoise) brains are among the least studied mammalian brains because of the difficulty of collecting and histologically preparing such relatively rare and large specimens. Among cetaceans, there exist relatively few studies of the brain of the dwarf sperm whale (Kogia simus). Magnetic resonance imaging (MRI) offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Therefore, MRI has become a critical tool in the study of the brain of cetaceans and other large species. This paper represents the first MRI-based anatomically labelled three-dimensional description of the dwarf sperm whale brain. Coronal plane sections of the brain of a sub-adult dwarf sperm whale were originally acquired and used to produce virtual digital scans in the other two orthogonal spatial planes. A sequential set of images in all three planes has been anatomically labelled and displays the proportions and positions of major neuroanatomical features.

Anatomy and three-dimensional reconstructions of the brain of a bottlenose dolphin (Tursiops truncatus) from magnetic resonance images.

Cetacean (dolphin, whale, and porpoise) brains are among the least studied mammalian brains because of the formidable challenge 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.

Magnetic resonance imaging and three-dimensional reconstructions of the brain of a fetal common dolphin, Delphinus delphis.

To demonstrate the kinds of data that can be obtained non-destructively and non-invasively from preserved museum specimens using modern imaging technology the head region of a whole body fetal specimen of the common dolphin, Delphinus delphis, aged 8-9 months post-conception, was scanned using Magnetic Resonance Imaging (MRI). Series of scans were obtained in coronal, sagittal and horizontal planes. A digital three-dimensional reconstruction of the whole brain was prepared from the coronal series of scans. Sectional areas and three-dimensional volumes were obtained of the cerebral hemispheres and of the brainstem-plus-cerebellum. Neuroanatomical features identified in the scans include the major sulci of the cerebral hemispheres, well-differentiated regions of gray and white matter, the mesencephalic, pontine, and cervical flexures, the "foreshortened" appearance of the forebrain, and the large auditory inferior colliculi. These findings show that numerous features of the fetal common dolphin brain can be visualized and analyzed from MRI scans.

Relationships between drug activity in NCI preclinical in vitro and in vivo models and early clinical trials.

An analysis of the activity of compounds tested in pre-clinical in vivo and in vitro assays by the National Cancer Institute's Developmental Therapeutics Program was performed. For 39 agents with both xenograft data and Phase II clinical trials results available, in vivo activity in a particular histology in a tumour model did not closely correlate with activity in the same human cancer histology, casting doubt on the correspondence of the pre-clinical models to clinical results. However, for compounds with in vivo activity in at least one-third of tested xenograft models, there was correlation with ultimate activity in at least some Phase II trials. Thus, an efficient means of predicting activity in vivo models remains desirable for compounds with anti-proliferative activity in vitro. For 564 compounds tested in the hollow fibre assay which were also tested against in vivo tumour models, the likelihood of finding xenograft activity in at least one-third of the in vivo models tested rose with increasing intraperitoneal hollow fibre activity, from 8% for all compounds tested to 20% in agents with evidence of response in more than 6 intraperitoneal fibres (P< 0.0001). Intraperitoneal hollow fibre activity was also found to be a better predictor of xenograft activity than either subcutaneous hollow fibre activity or intraperitoneal plus subcutaneous activity combined. Since hollow fibre activity was a useful indicator of potential in vivo response, correlates with hollow fibre activity were examined for 2304 compounds tested in both the NCI 60 cell line in vitro cancer drug screen and hollow fibre assay. A positive correlation was found for histologic selectivity between in vitro and hollow fibre responses. The most striking correlation was between potency in the 60 cell line screen and hollow fibre activity; 56% of compounds with mean 50% growth inhibition below 10(-7.5) M were active in more than 6 intraperitoneal fibres whereas only 4% of compounds with a potency of 10(-4) M achieved the same level of hollow fibre activity (P< 0.0001). Structural parameters of the drugs analysed included compound molecular weight and hydrogen-bonding factors, both of which were found to be predictive of hollow fibre activity.

Anatomy and three-dimensional reconstructions of the brain of the white whale (Delphinapterus leucas) from magnetic resonance images.

Magnetic resonance imaging offers a means of observing the internal structure of the brain where traditional procedures of embedding, sectioning, staining, mounting, and microscopic examination of thousands of sections are not practical. Furthermore, internal structures can be analyzed in their precise quantitative spatial interrelationships, which is difficult to accomplish after the spatial distortions often accompanying histological processing. For these reasons, magnetic resonance imaging makes specimens that were traditionally difficult to analyze, more accessible. In the present study, images of the brain of a white whale (Beluga) Delphinapterus leucas were scanned in the coronal plane at 119 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 such structures as the corpus callosum, internal capsule, cerebral peduncles, cerebral ventricles, certain thalamic nuclear groups, caudate nucleus, ventral striatum, pontine nuclei, cerebellar cortex and white matter, and all cerebral cortical sulci and gyri.

Molecules for the millennium: how will they look? New drug discovery year 2000.

A new approach to cancer drug discovery targets molecules important in cancer pathogenesis. This approach is thought to be of greater promise than the antiproliferative screens which discovered cytotoxic agents and dominated cancer drug discovery for 60 years. However, one cannot lose sight of the fact that these targets exist in the cellular environment consisting of many additional influences on target function, and that effective drug treatment will take into account drug uptake, metabolism and elimination at the level of the cell as well as the organism. A key goal is to define for the new millennium a path to cancer drug discovery and development which accounts for the cancer cell phenotype in its totality rather than as arising solely from single molecular targets. The US National Cancer Institute maintains a cell-based drug discovery screen which can define a context for drug action in the milieu of more than 300 molecular targets and thousands of gene expression patterns which have been measured in the 60 human tumour cell lines which comprise the screening panel. The challenge of the millennium will be addressed by molecules active against defined targets but with selectivity of action occurring in the milieu of deregulated cancer cell biology in all its aspects.

Cell line-directed screening assay for inhibitors of thioredoxin reductase signaling as potential anti-cancer drugs.

We have used a cell line-directed screening approach (CDSA) to identify novel inhibitors of the thioredoxin reductase signaling pathway which contributes to the transformed phenotype of some human tumors. Two 2-imidazolyl disulfide compounds, previously identified as inhibitors of thioredoxin reductase, were screened for growth inhibitory activity in the National Cancer Institute (NCI) human cancer cell line panel. The COMPARE pattern recognition algorithm was used to identify similar compounds from > 60,000 compounds in the NCI investigational drug database. Of 47 nondiscreet compounds tested in a thioredoxin reductase/thioredoxin insulin reduction assay, 37 (77%) were inhibitors with IC50s < or = 10 micrograms/ml and 15 of those (32%) had IC50s < or = 1 microgram/ml. These compounds were all as selective or more selective for thioredoxin reductase than for glutathione reductase, while three compounds were inhibitors of thioredoxin. In comparison to CDSA, the number of compounds with IC50s < or = 1 microgram/ml identified by screening of 52 compounds from the database whose growth inhibiting activity was unrelated to the activity of the disulfide compounds was only 2%. Screening of 221 randomly selected natural products gave only 3% of compounds with IC50s < or = 1 microgram/ml. Thus, the CDSA using data from the NCI cancer cell panel and known inhibitors of the selected target as seed compounds can greatly increase hit rates, compared with random screening, for identifying novel inhibitors of a target, in this case thioredoxin signaling.

Phylogeny through brain traits: more characters for the analysis of mammalian evolution.

We have assembled data on nine brain traits, in addition to the fifteen we have previously described, which provide new evidence for assessing mammalian relationships. States of these characters are tabulated as they occur in each of 152 mammalian species, providing data in numerically ordered form, useful for multiple analyses of phylogenetic relationships in programs which take into account variations in several different characters simultaneously. Derived states of each of the nine traits are characteristic of certain restricted groups of mammals; (1) mirroring of the complete SI body representation in isocortex (anthropoid primates); (2) loss of the accessory olfactory bulbs (sirenians, cetaceans, most bats, catarrhine primates); (3) Rindenkerne, clumps of cell bodies in layer 6 of cerebral cortex (sirenians); (4) posteriorly-pointing digits in the SI body representation (bats, both mega- and micro-); (5) equivalent tectopetal connections to the anterior colliculus of one side from both retinas, rather than predominantly from the contralateral retina (primates and megabats); (6) loss of lamination in dorsal cochlear nuclei (anthropoid primates, bats, seals, sirenians, cetaceans); (7) separation of claustrum from cerebral cortex (diprotodont marsupials, carnivores, artiodactyls, perissodactyls, hyracoids, cetaceans and primates), (8) presence of a complete secondary (SII) somatic sensory region of cerebral cortex (therians-all extant mammals other than monotremes), and (9) presence of a distinct external cuneate nucleus among the nuclei of the dorsal columns (all mammalian groups except monotremes and sirenians). Two examples of phylogenetic trees derived from these data are presented. These sample trees maintain the segregation of the monotremes and the marsupials, and the basic dichotomy of placentals seen in our earlier trees based entirely on brain data. They also show: an orderly sequence of bifurcations (rather than the commonly seen multifurcation near the base of the radiation) in the reconstruction of placental relationships; extremes of derivation for the Cetacea, the Chiroptera, and the Sirenia (in concordance with trees based on other data); a ferungulate association of Carnivora, Perissodactyla, Artiodactyla, Hyracoidea and Sirenia; and an assemblage of related Dermoptera, Primates, Scandentia, and Chiroptera which in this model also includes Insectivora and Macroscelidea. Analyses based on brain characters can reinforce conclusions based on other data, while at the same time introducing new ideas about relationships. Neural traits provide a source of data independent of those commonly used in phylogenetic analysis, and are extremely valuable for testing old hypotheses and for introducing new ones.(ABSTRACT TRUNCATED AT 400 WORDS)

Percutaneous absorption and metabolism of lonapalene in psoriatic skin.

The percutaneous absorption and metabolism of lonapalene (6-chloro-2,3-dimethoxynaphthalene-1,4-diol-diacetate; RS-43179), a topically effective 5-lipoxygenase inhibitor, has been measured in six subjects with stable plaque-type psoriasis of the lower extremities. Lonapalene readily penetrates psoriatic skin, is rapidly and completely metabolized, and is almost entirely excreted in the urine. Unexpectedly we observed a trend for thigh (T) plaque skin to be more permeable than lower leg (LL) plaque skin as measured by total absorption (T, 44.8 +/- 13.4%; LL, 24.9 +/- 12.6% applied dose excreted), peak plasma levels (T, 209 +/- 107; LL, 146 +/- 81 ng Eq/ml), and peak rate of urinary excretion (T, 591.7 +/- 112.2; LL, 318.4 +/- 143.9 micrograms Eq/hr). There were also differences in the metabolic profiles between the two sites as measured by the quantity and proportion of dealkylated and conjugated products excreted in the urine.

Manatee cerebral cortex: cytoarchitecture of the frontal region in Trichechus manatus latirostris.

Members of the order Sirenia are unique among mammals in being the only totally aquatic herbivores. They display correspondingly specialized physiological, behavioral and anatomical features. There have been few reports concerning sirenian neuroanatomy, and most of these have consisted of gross anatomical observations. Our interest in Sirenia stems from the desire to understand neuroanatomical specializations in the context of behavior and the effort to elucidate trends in mammalian brain evolution. The architecture of frontal regions of cerebral cortex was investigated in several brains of the Florida manatee, Trichechus manatus latirostris. Through observation of sections stained for Nissl substance or myelinated fibers, several distinct cortical areas were identified on the basis of laminar organization. These range from areas with poorly defined laminae to those having 6 well-defined layers, some of which exhibit sublayers. Two cortical areas exhibit pronounced cell clusters in layer VI, and these stain positively for acetylcholinesterase and cytochrome oxidase. We hypothesize that these clusters may be involved in perioral tactile bristle function. Certain of our findings are consistent with previous observations in the literature on the brains of dugongs. On the basis of their lamination patterns, these frontal cortical areas appear to be organized into concentric zones of allocortex, mesocortex and isocortex.

Kinesthetic cortical area anterior to primary somatic sensory cortex in the raccoon (Procyon lotor).

Extracellular microelectrode recording of cortical unit activity, with subsequent histological examination, was used to determine the extent, organization, and cytoarchitecture of the zone of muscle afferent projections (kinesthetic cortex) anterior to the primary somatic sensory cortex in anesthetized raccoons. Activity was evoked in response to mechanical stimulation of muscles from which the overlying skin had been dissected away. Most kinesthetic responses were elicited in a contiguous cortical area, which included: the anterior bank of the lateral arm, and the fundus and posterior bank of the medial arm of the medial central sulcus; and the anterior two-thirds of the interfundic rise within the interbrachial sulcus. Some responses were recorded in a separate small area of the anterior bank at the medial end of the lateral central sulcus. Somatotopy was evident with forelimb represented lateral to hindlimb. Proximal limb muscles were represented in the center of the medial central sulcus; distal muscle projections were medial (hindlimb) or lateral (forelimb) in the same sulcus. Most representations were of flexor and extensor muscles of the contralateral carpus and forepaw digits. Activity at a given recording locus in the kinesthetic area could be elicited by both flexor and extensor muscles, which acted about a common joint. Low amplitude units evoked by cutaneous stimulation of the dissected skin were recorded in the kinesthetic area; these were from receptive fields of skin that normally overlay the muscles whose higher-amplitude evoked kinesthetic units were represented in that same recording locus. The kinesthetic zone was anterior to primary somatic sensory cortex, where the outer stripe of Baillarger and granular layer IV become attenuated. In the hindlimb muscle representation area, the additional criterion of area 3a (large pyramidal cells in layer V) was seen. However, no cytoarchitecture could be identified that was consistently associated with the kinesthetic cortex.

Distribution of cells projecting to thalamus vs. those projecting to cerebellum in subdivisions of the dorsal column nuclei in raccoons.

To learn the distribution of cells projecting to the thalamus, as opposed to the cerebellum, in the mechanosensory nuclei of the dorsal medulla of raccoons, we analyzed the retrograde transport of horseradish peroxidase from the ventrobasal complex of the thalamus and from the cerebellum. We found six nuclear regions projecting heavily to the thalamus with very small projections to the cerebellum: Bischoff's, central cuneate, central gracile, rostral cuneate, rostral gracile nuclei, and cell group z. Two regions showed heavy projections to the cerebellum with no projections to the thalamus: the lateral portion of the external cuneate nucleus and the compact portion of cell group x. Four regions showed more equivalent projections to both target regions: basal cuneate, medial portion of the external cuneate nucleus, medial tongue extension of the external cuneate nucleus, and reticular portion of cell group x. Three more ventral regions were labeled: lateral cervical nucleus from thalamic injections but not from cerebellar injections; central cervical nucleus from cerebellar injections, which crossed the midline, but not from thalamic injections; and lateral reticular nucleus from both target regions. In most medullary regions, most cells project to one target and very few project to the other; we suggest that the cells projecting to the minor target convey samples of the information going to the major target.

Medullary sources of projections to the kinesthetic thalamus in raccoons: external and basal cuneate nuclei and cell groups x and z.

In raccoons and other mammals, a pathway for kinesthetic sensation (from muscles, fascia, tendons, and joints) reaches the anterodorsal cap of the ventrobasal thalamus and the anteriormost part of the somatic sensory cerebral cortex. To find the medullary component of this kinesthetic pathway in raccoons, small injections of horseradish peroxidase were made in the thalamus under guidance of simultaneous electrophysiological recording from kinesthetic projections. As determined by retrograde labeling following these injections, kinesthetic thalamic subregions receive projections as follows: caudomedial from cells in the external cuneate nucleus and its medial tongue, rostromedial from cells in basal cuneate nucleus, and rostrolateral from cells in cell group z and the reticular division of cell group x. Electrophysiological recording showed kinesthetic representations in each of these medullary regions. Labeled cells were also observed in the infratrigeminal subnucleus of the lateral reticular nucleus. Cats have kinesthetic projections to the thalamus from the basal cuneate and cell group z; raccoons (and monkeys) have these plus projections from the external cuneate and cell group x. This suggests that the kinesthetic projection system in raccoons and monkeys is expanded in correlation with their more dextrous use of the hand.

Demarcations of the mechanosensory projection zones in the raccoon thalamus, shown by cytochrome oxidase, acetylcholinesterase, and Nissl stains.

To determine anatomically the boundaries and internal organization of the kinesthetic and cutaneous mechanosensory regions of the ventrobasal thalamus, alternate section series from electrophysiologically mapped tissues from 14 raccoons were stained for cytochrome oxidase, myelinated fibers, acetylcholinesterase, and Nissl substance. Microelectrode tracks, along with electrolytic lesions placed as tissue markers, reveal that the mechanoreceptor projection zones have higher cytochrome oxidase and lower acetylcholinesterase staining than some neighboring regions. Both these enzymatic stains reveal particularly sharp boundaries separating the mechanoresponsive region, from the lateral posterior nucleus dorsally and from the ventroposterior inferior nucleus ventrally. The kinesthetic projection zone is often separated from other mechanoreceptor projections by bundles as well as laminae of myelinated fibers, similar to those separating cutaneous projections from distinct body parts. These subdivisions are particularly well marked by the cytochrome oxidase stain. The combination, in neighboring sections, of the use of the several stains adds considerably to the visible delineation of these functionally distinct regions, beyond what can be seen in Nissl-stained sections.

Organization of postcranial kinesthetic projections to the ventrobasal thalamus in raccoons.

To determine the presence and organization of kinesthetic, as compared with other mechanosensory projection zones in the thalamus of raccoons, unit-cluster responses to mechanical stimulation of the postcranial body were mapped electrophysiologically in the thalami of 14 raccoons anesthetized with Dial-urethane. A distinct zone of kinesthetic projections (from receptive fields in muscles, tendons, and joints) was found in the rostral and dorsal aspects of the mechanosensory projection zone. These projections are somatotopically organized: those from axial structures lie dorsalmost and those from successively more distal limb regions are successively more caudoventral. The kinesthetic forelimb representation is large and lies rostrodorsal to a large central core of cutaneous projections from the forepaw digits. A few scattered kinesthetic projections were found at the caudal edge of the sensory thalamic region. The large, spatially and somatotopically distinct kinesthetic projection zone in the thalamus parallels those seen in the cortex and medulla of raccoons. Similar findings in monkeys, and suggestions from data in cats and humans support the hypothesis of a distinct pathway to the cortex for kinesthetic information in all mammals.

Organization of intracortical and commissural connections in somatosensory cortical areas I and II in the raccoon.

The organization of intracortical and callosal projecting cell bodies was examined in somatosensory representation areas I (SI) and II (SII) of the raccoon by use of horseradish peroxidase (HRP) or horseradish peroxidase-wheat germ agglutin (HRP-WHA). HRP and HRP-WHA were injected into commissurally and noncommissurally connected subdivisions of SI and SII. Injection sites in SII were identified electrophysiologically. Results were obtained from transverse sections in which the HRP was visualized with the aid of the substrates dihydrochlorobenzidine or tetramethyl benzidine in the presence of hydrogen peroxidase. The principal findings were the following: (1) there are reciprocal connections between SI and SII; (2) in SI the intracortically projecting cell bodies and terminals are located primarily in sulcal cortex; (3) intracortically projecting neurons in SI are located primarily in layers III whereas in SII they are located principally in layers III and V; (4) there are connections between disparate areas within SI; and (5) there are intracortical connections between callosum-connected and acallosal regions in SII. These results are discussed with regard to the results of mapping studies of the SI, the significance of intracortical connections to the formation of sulci in SI, and the possible roles of nonhomotopic connections in the intermanual transfer of learning.

Brain traits through phylogeny: evolution of neural characters.

We have previously derived a hypothetical tree of the lines of mammalian descent, based upon a comprehensive numerical taxonomic cross-analysis of primitive and derived states of 15 brain traits in 38 representative species. In this communication we use this tree to describe the probable sequence of changes that have taken place in phylogenetic history. 2 characters proved to be multiply convergent, occurring in parallel in several disparate lines of descent. The remaining 9 characters each appeared in ancestors of one or another of the lineages and characterize related progeny.