The power of bioenergy-related standards to protect biodiversity.

The sustainable production of bioenergy is vital to avoiding negative impacts on environmental goods such as climate, soil, water, and especially biodiversity. We propose three key issues that should be addressed in any biodiversity risk-mitigation strategy: conservation of areas of significant biodiversity value; mitigation of negative effects related to indirect land-use change; and promotion of agricultural practices with few negative impacts on biodiversity. Focusing on biodiversity concerns, we compared principles and criteria set to address biodiversity and other environmental and social issues in seven standards (defined here as commodity-based standards or roundtables, or relevant European legislation): five voluntary initiatives related to bioenergy feedstocks, the Renewable Transport Fuel Obligation (United Kingdom), and the European Renewable Energy Source Directive. Conservation of areas of significant biodiversity value was fairly well covered by these standards. Nevertheless, mitigation of negative impacts related to indirect land-use change was underrepresented. Although the EU directive, with its bonus system for the use of degraded land and a subquota system for noncrop biofuels, offered the most robust standards to mitigate potential negative effects, all of the standards fell short in promoting agricultural practices with low negative impacts on biodiversity. We strongly recommend that each standard be benchmarked against related standards, as we have done here, and that efforts should be made to strengthen the elements that are weak or missing. This would be a significant step toward achieving a bioenergy industry that safeguards Earth's living heritage.

Confirmation of the retinopetal/centrifugal nature of the tyrosine hydroxylase-immunoreactive fibers of the retina and optic nerve in the weaver mouse.

The number of tyrosine hydroxylase-immunoreactive fibers in the nerve fiber layer is increased in the retina of the weaver compared to control mice (Dev. Brain Res. 121 (2000) 113). To confirm the retinopetal/centrifugal nature of these fibers, a newly devised whole-mounted optic nerve technique allowed us to determine, during development, their first appearance within the optic nerve (post-natal day 12) compared to retina (post-natal day 13). One such fiber was also observed looping in the retina of a monkey fetus.

Dopaminergic innervation of the subthalamic nucleus in the normal state, in MPTP-treated monkeys, and in Parkinson's disease patients.

The existence of a dopaminergic innervation of the subthalamic nucleus (STN) has been demonstrated in rats but has remained controversial in primates. The aim of the present study was first to demonstrate the existence of a dopaminergic innervation of the STN in monkeys using tracing methods and then to quantify the loss of dopaminergic fibers in the parkinsonian state in monkeys and humans. Following injection of Fluoro-Gold into the STN of a vervet monkey (Cercopithecus aethiops), retrogradely labeled neurons were found to be scattered in all dopaminergic areas of the mesencephalon. Injection of biotin dextran amine into dopaminergic areas A8 and A9 of two monkeys resulted in anterogradely labeled axons located throughout the whole extent of the STN. Labeled axons that also expressed tyrosine hydroxylase (TH) were reconstructed from serial sections. Some terminal axonal arborizations had profuse branching and occupied much of the STN, and others were restricted to small portions of the nucleus. In TH-immunoreactive sections, numerous sparse, fine, and varicose TH-positive fibers were observed in the STN of normal monkeys and humans. Quantification of these TH-positive fibers revealed a 51% loss of TH-positive fibers in MPTP-intoxicated monkeys and a 65% loss in Parkinson's disease patients compared with their respective controls. These findings demonstrate the existence of a dopaminergic innervation of the STN in primates. The loss of dopaminergic innervation in MPTP-intoxicated monkeys and in Parkinson's disease patients may directly affect the activity of STN neurons and could participate in the hyperactivity of the structure.

Paradoxical increase of tyrosine hydroxylase-immunoreactive retinopetal fibers in the weaver mouse.

Weaver mice undergo apoptosis of the granule cell precursors of the cerebellum and nonapoptotic death of mesencephalic dopaminergic cells during post-natal development. In contrast, the number of retinal dopaminergic cells was transiently increased in weaver compared to control mice [C. Savy, E. Martin-Martinelli, A. Simon, C. Duyckaerts, C. Verney, C. Adelbrecht, R. Raisman-Vozari, J. Nguyen-Legros, Altered development of dopaminergic cells in the retina of weaver mice, J. Comp. Neurol. 1999;412:656-668]. While re-examining the retinas, we observed, in the nerve fiber layer, retinopetal tyrosine hydroxylase-immunoreactive fibers, which were dramatically increased in number throughout development and adulthood in the weaver compared to control mice.

Ultrastructural Studies of the Mode of Penetration by Phoma macdonaldii in Sunflower Seedlings.

ABSTRACT An ultrastructural investigation of the artificial inoculation of sunflower with Phoma macdonaldii conidia was undertaken using light, scanning, and transmission electron microscopy to elucidate the host-parasite relationship. The behavior of the conidia deposited on the cotyledon petiole was investigated at various time intervals after inoculation. Conidia adhesion and germination were observed first. The cotyledon petiole was invaded by the fungus directly through the cuticle and via stomata. Externally, the spore and germ tube were covered with a mucilaginous polysaccharide sheath of a cotton-like appearance and of variable thickness. At the time of penetration, the host cuticle was perforated mechanically. The cuticle was slightly depressed and no enzymatic alteration could be observed. The fungus did not form appressoria on the surface of the host tissues but developed an infection peg. As soon as the cuticle barrier was crossed, the fungus rapidly colonized the host parietal layer. In a first step, the plasmalemma of the host cell appeared to be stuck against the cell wall. As soon as the fungus passed through the epidermal cell wall to reach the host cytoplasm, the plasmalemma was disrupted, and the subsequent rapid breakdown of cell integrity favored the colonization of the tissues by the pathogen.

Altered development of dopaminergic cells in the retina of weaver mice.

Postnatal degeneration of dopaminergic (DA) cells is known to occur in mesencephalic nuclei of mutant weaver mice, whereas retinal DA content is reported to be unchanged in the adult animal. To determine whether morphological changes occur in the weaver retinal DA system, we compared weaver and control developing and adult retinas after tyrosine hydroxylase (TH) immunohistochemistry. The density and distribution of DA cells were analyzed using Dirichlet tessellation. Not only was no DA cell loss found in adult weaver retinas, but we even observed an increase in DA cells in weaver compared to control retinas between postnatal days 14 and 30. Furthermore, some unusual features were found during the latter period: atypical cells (representing a maximum of 12% of the whole DA cell population) were observed, and these differed from typical DA cells in terms of both location (slightly more external within the inner nuclear layer) and appearance (flat somata, round and clear nuclei, thick dendritic trunks emerging laterally and giving rise to horizontal processes). Some of the atypical cells were intermingled in a delicate network lying in a more outer focal plane than the main DA plexus. The expression of GIRK2, a G protein-related inward rectifying K(+) channel responsible for the weaver syndrome, was investigated. Although no GIRK2 labeling was demonstrated in DA cells, its possible involvement in the transient disturbances observed in the weaver DA retinal system is discussed.

Dopaminergic and GABAergic retinal cell populations in mammals.

A number of modern techniques now allow histologists to characterize subpopulations of retinal neurons by their neurotransmitters. The morphologies and connections of these chemically defined neurons can be analyzed precisely at both light and electron microscope levels and lead to a better understanding of retinal circuitry. The dopaminergic neurons form a loose population of special wide-field amacrine cells bearing intraretinal axons within the inner plexiform layer. One subtype, the interplexiform cell, sends an axon to the outer plexiform and outer nuclear layers. The number of interplexiform cells is variable throughout mammalian species. The GABAergic neurons form a dense and heterogeneous population of amacrine cells branching at all levels of the inner plexiform layer. The presence of GABA in horizontal cells seems to be species-dependent. Close relationships occur between dopaminergic and GABAergic cells. GABA antagonizes a number of dopaminergic actions by inhibiting both the release and synthesis of dopamine. This inhibition can be supported by GABA synapses onto dopaminergic cells, but GABA can also diffuse to its targets. Finally, GABA is also contained and synthesized in dopaminergic cells. This colocalization might be the basis of an intracellular modulation of dopamine by GABA.

Distribution and spatial geometry of dopamine interplexiform cells in the retina. II. External arborizations in the adult rat and monkey.

The morphology and distribution of dopaminergic interplexiform cells in adult rat and monkey retinas were analyzed to determine any correlation with the function of dopamine in the outer retinal layers. The retinas were processed as whole mounts for tyrosine hydroxylase immunohistochemistry. There was a network formed by the sclerally directed processes of interplexiform cells in the inner nuclear, outer plexiform, and outer nuclear layers running throughout the retina. Their density was higher in the superior retina than in the inferior retina of the rat and was especially high in the superior temporal quadrant. The external network in this quadrant was significantly less dense in the monkey than in the rat, as are the interplexiform cells. The somata of interplexiform and other dopaminergic cells were about the same size in both rats and monkeys. Computer-assisted reconstruction of external arborizations of individual cells showed that external processes lay very close to horizontal and photoreceptor cells and also to blood capillaries. Because they were long, thin, and highly varicose; branched at right angles; and often arose from an axon hillock, the external processes were identified as axons. Therefore, we define the dopaminergic interplexiform cells as multiaxonal neurons, with at least one outwardly directed axon that reaches the outer plexiform layer. The function of the network of external processes from the interplexiform dopaminergic cells is discussed in terms of modulating the release of dopamine to external layers.

Morphometry and distribution of displaced dopaminergic cells in rat retina.

The majority of dopaminergic (DA) cells, labeled by tyrosine hydroxylase (TH) immunohistochemistry, are located in the amacrine cell layer (i.e., the innermost sublayer of the inner nuclear layer) in the rat retina. We describe a small population of DA cells, observed in retinal wholemounts, that are displaced to either the inner plexiform layer (DAIcs) or the ganglion cell layer (DAGcs). Contrary to some other species, such cells are few in number in the rat retina. Their systematic study was made in young and adult retinas by retinal mapping, camera lucida drawing, and computer-aided three-dimensional reconstruction. Located predominantly in the superior temporal quadrant, they are observed as soon as the second postnatal day. Most of the morphometric parameters studied were not significantly different between the two types of displaced DA cells, despite the characteristic appearance of interstitial cells. Two hypotheses are proposed for the origin of their displacement: either it is accidental or programmed. Our results favor the former possibility.

[Acute exanthematous pustulosis during amoxapine treatment]. / Pustulose exanthématique aiguë au cours d'un traitement par amoxapine (Défanyl).

Toxidermia is a well-known complication of antidepressor therapy, often related to photosensitization. The authors report an original case of amoxapine-related acute generalized exanthematous pustulosis which regressed at drug withdrawal.

Spatial geometry of the dopamine innervation in the avascular area of the human fovea.

The dopamine (DA) innervation, labeled by tyrosine hydroxylase immunohistochemistry in a wholemounted human retina, is described in the avascular area of the fovea. Eleven DA neurons give rise to this innervation, among which five are interplexiform cells, so that the DA innervation consists of two plexuses: one is internal and is formed by the dendrites of all of the DA cells, and the other is external and is formed by the scleral processes of the interplexiform cells. Five concentric zones are delineated according to the focal plane in which the internal DA plexus is observed. The central zone 1 contains DA processes crossing in all directions. Zones 2 and 3 do not contain any cell bodies. In zone 3 the internal plexus begins to undergo a concentric arrangement, which is clearly observed in zones 4 and 5. The external DA innervation displays a different appearance in zones 1, 2, and 3, in which it consists of vertically oriented thin processes and terminals penetrating the outer nuclear layer, vs. zones 4 and 5 in which it consists of both the same type and horizontal processes lying in the outer plexiform layer. On the basis of DA-innervation appearance and distribution of labeled and unlabeled cell somata, it was concluded that zones 1, 2, and 3 contained the DA innervation of the foveola. DA processes filtering between photoreceptor cells are particularly well-observed in this region. This anatomical study of the DA innervation in the human fovea leads to a better understanding of the important role of DA in primate central vision and can be used as a reference for an approach of macular pathology.

Dopaminergic interplexiform cells displaced to the ganglion cell layer in the rat retina.

The reconstruction of dopaminergic interplexiform cells visualized by their tyrosine hydroxylase immunoreactivity in rat retinal wholemounts demonstrates that the immunoreactive processes observed in the inner nuclear and outer plexiform layers can belong to dopaminergic cell bodies located in the ganglion cell layer. An example of such a displaced interplexiform cell has been analyzed by camera lucida drawings, micrographic focal series and computer rotations.

Distribution and spatial geometry of dopamine interplexiform cells in the rat retina: I. Developing retina.

The morphology and distribution of dopaminergic interplexiform cells were analyzed in 9-day-old rat retinas processed as wholemounts for tyrosine hydroxylase immunohistochemistry. The mean number of dopaminergic interplexiform cells was estimated as about half of the total number of dopaminergic neurons in the immature retina, with a higher density in the temporal retina. Four interplexiform cells were individually analyzed and reconstructed with a computer system. Their arborizations could be divided into three different regions based on both their morphological features and their position within the retinal layers: (1) an internal arborization, spreading at the margin between the inner nuclear layer and the inner plexiform layer, composed of long, thick, somatofugal dendrites branching at acute angles, (2) an external arborization in the middle of the inner nuclear layer, formed by short, thin, varicose, recurved, axon-like processes branching at right angles, (3) and one or more scleral process(es), originating either from the cell body or from the internal arborization, running toward the outermost cell row of the INL, some of which reached the outer plexiform layer. Finally, analysis of the arborization network by computer simulations based on the 4 digitalized cells was compared with a nearest-neighbour analysis of cell body distribution. It showed that cell bodies are almost randomly distributed--at least in the inferior retina--but that an adjustment of dendritic growth and orientation probably occurs to ensure a homogeneous coverage of the retina with a constant degree of overlap in the adult. This report represents the first three-dimensional computer reconstruction of chemically identified neurons in the retina.

An image analysis morphometric method for the study of myelinated nerve fibers from mouse trigeminal root.

For the morphometric light microscopic study of myelinated fibers in mouse trigeminal root, it was necessary to write: (1) an entirely automatic analysis program for the myelinated axons inside the myelin sheath, based on the detection of the myelin sheaths, and (2) an interactive analysis program for the myelinated fibers outside the myelin sheath, due to the high density of compactness of the myelinated fibers based on an indirect fiber individualization by reconstructing them from their axons. In the latter, a semiautomatic correction method (drawing the profile contours with a light pen) allowed compensation for the failures of the automatic method, except for the smallest fibers, which represented 8% of the total. Using these programs, 95% of the axons could be measured and 92% of the myelinated fibers whose axons were analyzed could be measured. The area-equivalent diameter was independent of the detection method; it is a correct-size measurement parameter for axons and fibers that is unrelated to their shape. The projected diameter, an estimation of the perimeter obtained by measurement of the profile projections, depended upon the detection method because the profile contour was influenced by the detection method; it thus takes into account the profile shape. For myelinated fibers, whose analysis program used two detection methods (automatic and semiautomatic), there was an average difference of 16% between the projected diameters obtained with these two methods, whereas the equivalent diameter value was the same. The fiber circularity factor could not be precisely estimated because of the detection error; the axon circularity factor was more reliable since the axon detection was completely automatic.

Morphological alterations in subcortical vibrissal relays following vibrissal follicle destruction at birth in the mouse.

Morphological modifications of two subcortical vibrissal relays were analyzed, following destruction of vibrissal follicles in newborn mice. The volume of the nucleus interpolaris (NI) of the trigeminal nuclear complex in the brainstem decreased by 33%, while the number of its neuronal perikarya decreased only moderately. Vibrissal deafferentation caused no shrinkage of the ventrobasal complex (VB). In the damaged medial vibrissal part of VB (VBm), however, neuronal density was higher than normal, indicating the prevention or retardation of physiologically programmed cell death in the afferentation deprived thalamic somatosensory relay station. It is suggested that the difference in neuron density produced by deafferentation is related to the states of maturation at birth of the two subcortical vibrissal relays. Following vibrissal deafferentation the basic organization of the synaptic neuropil appeared to be similar to the control. Quantitative electron microscopic (EM) analysis revealed, however, an increased number of axon terminals with ovoid synaptic vesicles in both deafferented relay stations. The increased density of gamma-aminobutyric acid (GABA)-immunostained boutons observed in the VBm following vibrissal deprivation suggested a compensatory increase most probably of the inhibitory axon endings. Quantitative EM analysis also provided evidence that many or most of the specific afferent terminals in the damaged VBm were not identical with but were substitutes for the original "vibrissal" specific afferents. Forty percent of all "specific" afferents were shown to be modified corticothalamic terminals. The modification and the resemblence of some cortical endings to specific afferents demonstrated the morphogenetic plasticity of synaptogenesis in these terminals during development as well as the importance and inductive potential of the postsynaptic target in the differentiation of presynaptic axon terminals.

[Organization of the nervous system after coagulation of the follicles of mystacial vibrissae in the newborn mouse: an example of neuronal plasticity]. / L'organisation du système nerveux après coagulation des follicules des vibrisses mystaciales chez la souris nouveau-née: un exemple de plasticité neuronale.

In the mouse the vibrissae and the common fur of the head are a good model of the so called neural plasticity. The characteristics of this model are: the pattern of implantation of the vibrissae at the periphery and that of the arrangement of barrels in the contralateral cortical projection area of vibrissae as well as that of the "barreloïds" in the subcortical vibrissal relays (somato sensory thalamus and trigeminal nuclear complex) are homeomorphic with one another. Each barrel and "barreloïd" receives projections from one vibrissa. Moreover at the level of the cortex these projections are also in register with projections from ipsilateral vibrissae. Head fur hairs project to well defined but entirely distinct areas. Destruction of vibrissae follicles at birth beside preventing barrel and barreloïd formation in the CNS, leads to several morphological changes: degeneration of the primary sensory neurons innervating vibrissae in the trigeminal ganglion, thus degeneration of their central axons and the corresponding terminals in the trigeminal vibrissal relays changes in the distribution of the activity of succinate dehydrogenase in the IVth layer of the cortical vibrissal area and in the corresponding subcortical relays, from the normal discrete (barrel hollow) pattern--corresponding to the clustered vibrissal afferents--to a continuous band, keeping a normal level of activity, excepted in the trigeminal vibrissal relays and a remarkable preservation of cortical thickness but a notable atrophy in the trigeminal vibrissal projection areas. Beside upsetting the anatomy vibrissae follicle destruction causes marked functional changes an outstanding take-over of the deafferented cortical vibrissal area (still identifiable from projections of vibrissae ipsilateral to it) by the head fur hairs this take over exist also in the subcortical vibrissal relays a change in the thalamo-cortical connections. Modifications in the organization of connections are initiated by the loss of the primary sensory neurons innervating vibrissae, in the trigeminal ganglion and results only from early lesions. In mice lesioned when adults the loss of primary sensory neurons is less important and functional take over by the common fur is not observed.

A morphometric study of mouse trigeminal roots after unilateral destruction of vibrissae follicles at birth.

Trigeminal sensory roots were studied in neonatal mice. On the deafferented side, the surface area of the cross-section through the sensory root is diminished by 31% and the number of myelinated fibers is reduced by 21%, but the proportion between myelinated and unmyelinated fibers remains unchanged. The distribution of axonal diameters, analysed in 7 dorso-ventral scanning bands through the sensory roots, indicates a loss or eventually an atrophy of large myelinated axons in the medial two thirds of the sensory root. In both control and deafferented sides the diameter of the myelinated fiber (outside the myelin sheath) is proportional to the axon diameter (inside the myelin sheath). Our results confirm the loss of most of the neurons innervating vibrissae and the lack of regeneration or sprouting in the deafferented root in the newborn mouse.

[Histological changes in the somatosensory thalamus after unilateral coagulation of vibrissa follicles of the muzzle of the newborn mouse]. / Modifications histologiques dans le thalamus somatosensoriel après coagulation unilatérale des follicules des vibrisses du museau chez la Souris nouveaunée.

Light microscopic study of the thalamic ventro-basal complex (VB), after unilateral coagulation of vibrissae follicles in newborn mouse, revealed an excess of neuronal perikarya on the controlateral "deafferented" side as compared to the normal side. The higher density of nerve cells was confined to the vibrissal relay in the medial part of VB nucleus (VBm), whereas the cell number in the non vibrissal-lateral part of this nucleus (VB1) remained on the control level. Electron microscopic investigation of the thalamic vibrissal relay has shown signs of a modified synaptogenesis on the "deafferented" side: (a) the number of specific afferents has diminished and in contrast to the normal side, most of the specific sensory terminals contain small spheroid synaptic vesicles and (b) the number of axon terminals with ovoid pleomorphic vesicles has been doubled.

[Localization of neurons innervating vibrissae in the mouse in the Gasserian ganglion: retrograde peroxidase transport study and morphometric analysis]. / Localisation dans le ganglion de Gasser des neurones innervant les vibrisses chez la souris: etude par transport retrograde de la peroxydase et analyse morphometrique.

Two methods were used in an attempt to localize within the trigeminal ganglion the neurons whose axons innervate mouse mystacial vibrissae. First, the loss in the bulk area occupied by neuronal cell bodies in the ophthalmo-maxillary part of the ganglion in two-month old mice, whose vibrissae follicles were coagulated unilaterally at birth, was evaluated morphometrically in four sectors of each section. Secondly, neurons labelled by the injection of peroxidase in the vibrissae follicles of adult mice were localized in the ganglion. The results indicate that the neurons which ensure the sensitive innervation of the vibrissae are situated in the median area of the ophthalmo-maxillary part of the ganglion, extending more rostrally than caudally, mainly in ventral position. A certain degree of somatotopy is demonstrated by the comparative study of neurons labelled by the injection of peroxidase in the anterior or posterior follicles. The neurons which correspond to the anterior vibrissae are mainly ventral, while they are both dorsal and ventral for the posterior vibrissae.

A morphometric study of mouse trigeminal ganglion after unilateral destruction of vibrissae follicles at birth.

A morphometric study of the trigeminal ganglion after unilateral vibrissae follicles' coagulation in newborn mice has shown the following: (a) a 42.8% decrease of the total volume of the ganglion on the deafferented side with reference to the normal side; a 61.5% decrease of the ophthalmic-maxillary part of the ganglion where neurons whose axons innervate vibrissae follicles are located, and only a 24.1% decrease in the common part; (b) a 54.8% decrease of the neuronal cell body volume in the ophthalmic-maxillary part and practically no change in the common part, and (c) a 64.5% decrease of the volume occupied by the nerve fibers in the ophthalmic-maxillary part and only a 28.1% decrease in the common part. A comparison of the section areas in ganglion and of the bulk area of neuronal cell bodies at different levels has also been performed. Counting of the neuronal cell bodies in the ophthalmic-maxillary part of the ganglion indicated a mean neuronal loss of 36.5%. Peripheral reinnervation of the common fur by regenerated axons of neurons which previously innervated vibrissae, although unlikely, cannot be completely excluded.