Production and dispersal of Colletotrichum gloeosporioides spores on Stylosanthes scabra under elevated CO2.

This paper reports the effect of twice-ambient (700 ppm) atmospheric CO(2) concentration on infection, disease development, spore production and dispersal of the anthracnose pathogen Colletotrichum gloeosporioides in susceptible (Fitzroy) and partially resistant (Seca) cultivars of the tropical pasture legume Stylosanthes scabra under controlled environment and field conditions. Reduction in plant height due to anthracnose was partially compensated for by growth enhancement at elevated CO(2) in Fitzroy but not in Seca. Anthracnose severity was reduced under elevated CO(2) although the reduction was only significant in Fitzroy. Delayed and reduced germination, germtube growth and appressoria production were partly responsible for the reduced severity. Despite an extended incubation period, C. gloeosporioides developed sporulating lesions faster and produced more spores per day within the same latent period at high CO(2) and ambient CO(2). When Fitzroy seedlings grown at 700 ppm CO(2) were exposed to pathogen inoculum under field conditions, they consistently developed more severe anthracnose with more lesions than seedlings grown at ambient CO(2). The environmental variable, which correlated most strongly with the dispersal and infection of C. gloeosporioides spores in the field, was relative humidity in plant canopy. We have shown that an enlarged Stylosanthes canopy under elevated CO(2) can trap more spores, which can lead to more severe anthracnose under favorable weather. The implications of these findings for perennial Stylosanthes pastures are discussed.

The effect of the potential antipsychotic ORG 5222 on local cerebral glucose utilization in freely moving rats.

The effects of administration of different doses of the potential antipsychotic Org 5222 (0.01 and 0.1 mg/kg i.v.) upon local cerebral glucose utilization (LCGU) in 102 anatomically discrete brain regions of freely moving male Wistar rats were studied with the quantitative autoradiographic [14C]2-deoxyglucose technique. Glucose utilization was significantly changed after treatment with 0.01 and 0.1 mg/kg i.v. Org 5222 in two and four brain areas, respectively. Treatment with 0.01 mg/kg Org 5222 significantly reduced LCGU in the basal thalamus (the ventral posterior medial (VPM) and lateral (VPL) nuclei). After administration of 0.1 mg/kg Org 5222, significant reductions were seen in the basal thalamus (VPL and VPM) and the medio dorsal thalamic nuclei. A highly significant elevation in LCGU was observed in the lateral nucleus of the habenula. The results show that Org 5222 selectively reduced LCGU in thalamic structures and had no or minimal effect on limbic, cortical and nigrostriatal structures, suggesting that Org 5222 may have antipsychotic potential, without inducing cognitive and extrapyramidal side-effects.

Ecology of a simple plant-herbivore system. Biological control of Salvinia.

The salvinia-herbivore system has been investigated in more detail than most, because of its relative simplicity due to the absence o f sexual and dormant stages in the plant's life cycle, the apparent genetic uniformity of the plant, the absence of water stress, the uniformity of the water surface habitat and the absence of herbivores outside the plant's native range. This review describes how biological control of salvinia was achieved and discusses ecological principles illustrated by salvinia and its herbivores.

Circadian variations in local cerebral glucose utilization in freely moving rats.

Sokoloff's [14C]2-deoxyglucose method has been applied to investigate circadian variations in local cerebral glucose utilization (LCGU). Freely moving rats were tested during two phases of the circadian light/dark cycle. In the rats tested during darkness, elevations in LCGU, when compared with animals tested during the light period, were observed in the primary and secondary visual cortex, the primary auditory cortex, the lateral geniculate nucleus, the amygdala, the entorhinal cortex, the hippocampus, the substantia nigra and the cerebellum. A reduction in LCGU was observed in the suprachiasmatic nucleus.

The neuropeptide, Org 5878 (desenkephalin-gamma-endorphin, DE gamma E), affects local cerebral glucose utilization in freely moving rats.

The effect of the antipsychotic peptide, Org 5878 (desenkephalin-gamma-endorphin, beta-endorphin-(6-17), on local cerebral glucose utilization was studied in freely moving male Wistar rats. Org 5878 (20 micrograms/kg, i.v.) or saline were given acutely and local cerebral glucose utilization was measured in 116 brain structures. Glucose uptake was not altered by Org 5878 in most brain areas, including areas of the nigrostriatal system, the cortex and the thalamus. However, significant reductions in glucose uptake were observed in the ventral tegmental area, the diagonal band complex, the hippocampus, the amygdala, the interpeduncular nucleus, the reticular nucleus of the thalamus and the cerebellum. These results indicate that the nigrostriatal and cortico-thalamic systems remain unaffected but the activity of the mesolimbic ventral tegmental area and of major target areas of cholinergic basal forebrain structures is selectively reduced following Org 5878 administration. It is concluded that the effect of Org 5878 on local cerebral glucose utilization is distinct from and more selective than that of antipsychotics currently used in the clinic.

Local cerebral glucose uptake in anatomically defined structures of freely moving rats.

Two limitations of the classical [14C]2-deoxyglucose (DG) method are the severe stress to which the restrained animals are exposed, and the difficulties with the anatomical analysis of the autoradiograms. The present study describes modifications which circumvent these limitations. Firstly, rats are provided with two chronic indwelling cannulas to allow blood sampling under unrestrained conditions. Absence of stress is demonstrated by low plasma corticosterone levels in the cannulated rats at the start of the experiment. The second modification concerns the image analysis system. The image of the autoradiogram is superimposed on the image of the identical histologically stained section in order to improve the accuracy of the structure identification. This approach enables the operator to delineate the anatomical brain structure in the histologically stained section and quantify the glucose uptake in the autoradiogram generated from this section. The reproducibility of the present quantitative measuring system is illustrated by glucose uptake measurements in different laminar zones of the various fields in the dorsal hippocampal formation. It is concluded that the present technical improvements of the classically applied [14C]2-deoxyglucose technique provide favourable conditions for the quantitative study on cerebral glucose uptake in normally behaving animals.

Reciprocal connections of the insular and piriform claustrum with limbic cortex: an anatomical study in the cat.

The connections of the claustrum with non-isocortical limbic and paralimbic cortex in the cat are described, using the anterograde transport of tritiated amino acids and the retrograde transport of various fluorescent tracers and of horseradish peroxidase conjugated to the lectin wheatgerm agglutinin. It could be demonstrated that the claustrum, in addition to its connections with sensory-related areas, is reciprocally and bilaterally connected with widespread limbic and paralimbic cortical regions. These connections are organized such that the area of origin of claustral efferents to a certain cortical region coincides with the area of termination in the claustrum of afferents from that same cortical region. A rostrocaudal topographical organization of the limbic-related connections of the claustrum is not very apparent. However, the results clearly demonstrate a dorsoventral topographical organization in the connections between the claustrum and the cortex. The ventral part of the claustrum has reciprocal connections predominantly with the entorhinal cortex, and possibly with the anterior olfactory nucleus and the prepiriform cortex. A more dorsally located part of the claustrum is preferentially connected with the orbitofrontal, the insular, the perirhinal, the anterior limbic, and the cingular cortices, and with parts of the subicular complex. The most dorsal portion of the claustrum is more heavily connected with parasensory and sensory cortices. It is concluded that the traditional subdivision of the claustrum into two discrete nuclei, i.e. the insular claustrum connected with the isocortex, and the piriform claustrum or endopiriform nucleus connected with the allocortex, does not reflect the actual organization of the cortical connections of the claustrum. The present data provide a more differentiated view, such that the ventral portion of the claustrum is reciprocally connected mainly with the olfactory-related cortices and the entorhinal cortex, whereas the cortical connections of progressively more dorsal parts of the claustrum gradually shift from limbic and paralimbic towards parasensory and sensory cortical connections. The significance of these findings is discussed in the light of a possible function of the claustrum in relation to corticocortical integration and memory processing.

Connections of the parahippocampal cortex in the cat. V. Intrinsic connections; comments on input/output connections with the hippocampus.

The present report is the last in a series of papers on the connectivity of the parahippocampal cortex in the cat, which in this species is considered to be composed of the entorhinal and perirhinal cortices. Injections of anterogradely transported tritiated amino acids and the retrograde tracers HRP, WGA-HRP, fast blue, or nuclear yellow were placed within the limits of the parahippocampal cortex. An analysis was made of the resulting pattern of anterograde labeling and of the distribution of retrogradely labeled neurons within the parahippocampal cortex. It appears that within the parahippocampal cortex of the cat a framework exists, which is composed of longitudinal and transverse connections, organized according to three principles: Medially directed projections originate mostly in superficial layers, whereas laterally directed fibers come from deep layers. The longitudinal connections span the entire rostrocaudal extent of the parahippocampal cortex, whereas the mediolateral extent of the transverse connections is in general more restricted. Based on the organization of these longitudinal and transverse connections four longitudinal zones are recognized. The lateral entorhinal cortex (LEA) projects both within the entorhinal cortex and to the perirhinal cortex, whereas the intrinsic projections of the medial entorhinal cortex (MEA) are confined to the entorhinal cortex. These results are discussed in conjunction with the main organizational features of the afferent and efferent connections of the parahippocampal cortex of the cat. The premise is made that the cytoarchitectonically defined subdivisions of the cortex can be grouped into four areas, each with its own set of fiber connections and subserving different functional roles. A lateral area, constituted by the perirhinal areas 35 and 36, and the caudally adjacent postsplenial cortex, serves as a peripheral area through which the rest of the parahippocampal cortex--i.e., LEA and MEA, and ultimately the hippocampal formation--reciprocally communicates with extensive neocortical, subcortical, and thalamic regions associated with higher-order behavior. The medial part of LEA, constituted by the ventrolateral (VLEA) and ventromedial (VMEA) divisions, has reciprocal connections with the hippocampal formation and with the cortex, partly via the perirhinal cortex, and is connected with a number of subcortical structures such as the amygdala and the striatum.(ABSTRACT TRUNCATED AT 400 WORDS)

Connections of the parahippocampal cortex. I. Cortical afferents.

In the present study in the cat the parahippocampal cortex denotes the caudoventral part of the limbic lobe and is composed of the entorhinal and perirhinal cortices. The cytoarchitecture of these areas and their borders with adjacent cortical areas are briefly discussed. The organization of the cortical afferents of the parahippocampal cortex was studied with the aid of retrograde and anterograde tracing techniques. In order to identify the source of cortical afferents, injections of retrograde tracers such as wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP), or the fluorescent substances fast blue or nuclear yellow, were placed in different parts of the parahippocampal cortex. In an attempt to further disclose the topographical and laminar organization of the afferent pathways, injections of tritiated amino acids were placed in cortical areas that were found to project to the parahippocampal cortex. The results of these experiments indicate that fibers from olfactory-related areas, the hippocampus, and other parts of the limbic cortex project only to the entorhinal cortex. The afferents from olfactory structures terminate predominantly superficially, whereas hippocampal and limbic cortical afferents are directed mainly to layers deep to the lamina dissecans. Paralimbic areas, including the anterior cingulate and the prelimbic cortices on the medial aspect, and the orbitofrontal and granular and agranular insular cortices on the lateral aspect of the hemisphere, project to the entorhinal cortex and medial parts of area 35 of the perirhinal cortex. These mostly mesocortical afferents terminate in both the superficial and deep layers of the entorhinal and perirhinal cortices. Parasensory association areas, which form part of the neocortex, do not project farther medially in the parahippocampal cortex than the perirhinal areas 35 and 36. These afferents mainly stem from a rather wide rim of neocortex that lies directly adjacent to area 36 and extends from the posterior sylvian gyrus via the posterior ectosylvian gyrus into the posterior suprasylvian gyrus. There is a rostrocaudal topographical arrangement in these projections such that rostral cortical areas distribute more rostrally and caudal parts project to more caudal parts of the perirhinal cortex. The cortex of the posterior suprasylvian gyrus contains the paravisual areas 20 and 21. The posterior sylvian gyrus most probably represents a para-auditory association area, whereas the most ventral part of the posterior ectosylvian gyrus may constitute a convergence area for visual and auditory inputs.(ABSTRACT TRUNCATED AT 400 WORDS)

Connections of the parahippocampal cortex in the cat. II. Subcortical afferents.

The organization of subcortical inputs to the parahippocampal cortex, which in the present study in the cat is considered to comprise the entorhinal and perirhinal cortices, was studied by using retrograde and anterograde tracing techniques. The results of the retrograde tracer horseradish peroxidase (HRP), HRP conjugated with wheat germ agglutinine (WGA-HRP), Fast Blue (FB) or Nuclear Yellow (NY] injections indicate that the entorhinal and perirhinal cortices receive inputs from the magnocellular basal forebrain and from distinct portions of the amygdaloid complex, the claustrum, and the thalamus. The two cortices are further projected upon by fibers from the supramamillary region of the hypothalamus, the ventral tegmental area of the mesencephalon, the dorsal raphe nucleus, the nucleus centralis superior, and the locus coeruleus. The entorhinal cortex, in addition, receives projections from the medial septum. As regards the projections from the amygdaloid complex, it was observed that the entorhinal cortex receives its heaviest input from the basolateral amygdaloid nucleus, whereas the perirhinal cortex receives a strong projection from the lateral nucleus and a weaker projection from the basomedial nucleus of the amygdala. Of the thalamic nuclei that project to the parahippocampal cortex, the nucleus reuniens is only connected with the entorhinal cortex, while fibers from the medial geniculate nucleus and the lateral posterior nucleus terminate in the perirhinal cortex. Injections of tritiated amino acid (3H-leucine) were placed in the medial septum, the dorsal and ventral claustrum, the basolateral and basomedial amygdaloid nuclei, and the nucleus reuniens of the thalamus. The results of these experiments demonstrate that, with the exception of the claustrum, these subcortical areas project mainly to the superficial layers I-III and the lamina dissecans of the parahippocampal cortex, and to a lesser degree to the deep layers V and VI.

Efferent connections of the prelimbic (area 32) and the infralimbic (area 25) cortices: an anterograde tracing study in the cat.

The projections from the caudal part of the medial frontal cortex, encompassing the prelimbic area (PL) and the infralimbic area (IL) (Brodmann's areas 32 and 25, respectively), were studied in the cat with the anterograde autoradiographic tracing technique. The results indicate that the projection fields of IL, in contrast to those of PL, are restricted almost exclusively to limbic structures. Whereas the major thalamic projections from PL reach the mediodorsal, anteromedial, and ventromedial nuclei, the medial part of the lateral posterior nucleus, and the parataenial and reticular nuclei, and weak projections from this area are directed to the nucleus reuniens and other midline nuclei, the nucleus reuniens is the major thalamic termination field of fibers arising from IL. Cortical areas that are reached by fibers originating in PL and, to a lesser degree, also in IL, include more rostral prefrontal areas (areas 8, 6, and 12), the agranular insular, and the rostral perirhinal cortices. In contrast, cortical areas that are more strongly related to IL include the cingulate, retrosplenial, caudal entorhinal, and perirhinal cortices and the subiculum of the hippocampal formation. Another prominent output of PL concerns projections to an extensive medial part of the caudate nucleus and the ventral striatum, whereas fibers from IL only distribute most ventrally in the striatum. In the amygdaloid complex, fibers from PL were found to reach the basolateral, basomedial, and central nuclei, and fibers from IL to distribute to the medial and central nuclei. PL furthermore projects to the claustrum and the endopiriform nucleus. Other structures in the basal forebrain, including the medial septum, the nuclei of the diagonal band, the preoptic area, and the lateral and dorsal hypothalamus are densely innervated by IL and only sparsely by PL. With respect to more caudal parts of the brainstem, projections from PL and IL appeared to be essentially similar. They reach the ventral tegmental area, the periaqueductal gray, the parabrachial nucleus, and in cases of PL injections were followed as far caudally as the pons.

Inputs from the olfactory bulb and olfactory cortex to the entorhinal cortex in the cat. I. Anatomical observations.

The spatial organization and laminar distribution of projections from the olfactory bulb and the anterior (PPCa) and posterior (PPCp) divisions of the prepiriform cortex to the entorhinal cortex were studied with anterograde (3H-leucine) and retrograde (WGA-HRP) tracing techniques. After 3H-leucine injections into the olfactory bulb transported labeling was seen over the lateral entorhinal area, except its most medial part, and over the rostral part of the medial entorhinal area. The labeling covers exclusively layer Ia. The lateral and medial entorhinal areas are also reached by fibers from the prepiriform cortex. The projection to the medial entorhinal area has not been described previously. Following injections of 3H-leucine into the PPCa transported labeling is present over the entire expanse of the entorhinal cortex and is located over layer Ib with the greatest density in its superficial part. Injections of 3H-leucine into the PPCp give rise to transported labeling over much of the entorhinal cortex. No labeling was found over the most medial parts of the medial subdivision (VMEA) of the lateral entorhinal area and the medial entorhinal area. Labeling occupies layer Ib, especially its middle part, and layers II and III. Both PPCa and PPCp appear to project most heavily to the dorsal (DLEA) and ventral (VLEA) subdivisions of the lateral entorhinal area. From the retrograde experiments it can be inferred that cells of layers II and III of the PPCa project predominantly to the DLEA, whereas those of the PPCp project predominantly to the VLEA. The MEA receives its heaviest projection from layer II of both PPCa and PPCp.(ABSTRACT TRUNCATED AT 250 WORDS)

Cortical afferents of the nucleus accumbens in the cat, studied with anterograde and retrograde transport techniques.

The cortical afferentation of the nucleus accumbens in the cat was studied with the aid of retrograde tracing techniques. Retrograde experiments were carried out with horseradish peroxidase or one of the fluorescent tracers Bisbenzimid, Nuclear Yellow and Fast Blue. In the anterograde experiments [3H]leucine and [35S]methionine were used as tracers. Following injections in the nucleus accumbens, retrogradely-labelled cells were found in the medial frontal cortex, the anterior olfactory nucleus, the posterior part of the insular cortex, the endopiriform nucleus, the amygdalo-hippocampal area, the entorhinal and perirhinal cortices and the subiculum of the hippocampal formation. In the medial frontal cortex most of the labelled cells were found in layers III and V of the prelimbic area (area 32 of Brodmann), but retrogradely-filled neurons were also present in the infralimbic area and in the caudoventral part of the lateral bank of the proreal gyrus. Retrogradely-labelled cells in the entorhinal and perirhinal cortices were located in the deep cellular layers. Following large injections in the nucleus accumbens, retrograde labelling in the subiculum extended from the most dorsal, septal pole to the most ventral, temporal pole. Injections of anterograde tracers were placed in the frontal cortex, the entorhinal and perirhinal cortices and the hippocampal formation. The prelimbic area was found to project via the internal capsule to mainly the rostral half of the nucleus accumbens, whereas in the caudal half of the nucleus only a lateral region receives frontal cortical fibres. Following injections in the infralimbic area only fibres passing through the nucleus accumbens were labelled. Afferents from the entorhinal and perirhinal cortices reach the nucleus accumbens by way of the external capsule and terminate mainly in a ventral zone of the nucleus accumbens. Afferents from the entorhinal area are distributed to the entire accumbens, whereas the termination field of the perirhinal afferents is largely restricted to the lateral part of the nucleus accumbens. Both the frontal cortex and the entorhinal and perirhinal cortices appear to project also to the nucleus caudatus and the tuberculum olfactorium. These cortical areas also project to the contralateral striatum. Both anterograde and retrograde tracing experiments demonstrated a topographical relationship between the subiculum and the nucleus accumbens. The ventral pole of the subiculum projects via the fornix to the medial part of the caudal half of the nucleus accumbens and to a small dorsomedial area in its rostral half. Successively more dorsal portions in the subiculum project to successively more ventrolateral parts in the rostral nucleus accumbens. The projection from the hippocampus was found to extend also to the tuberculum olfactorium. The results of the present study do not provide unambiguous criteria for the delimitation of the nucleus accumbens in the cat.

Divergent axon collaterals of rat locus coeruleus neurons: demonstration by a fluorescent double labeling technique.

The distribution of the noradrenaline-containing neurons of the rat locus coeruleus has been investigated with retrograde labeling techniques using two different fluorescent tracers. Injections were placed in the prefrontal cortex, the striatum, the thalamus, the hippocampus, the cerebellar cortex and the lumbar spinal cord. No evidence for locus coeruleus projections to the striatum was found. Injections in the cortex, thalamus and hippocampus revealed not only ipsilateral but also contralateral labeling of cells in the locus coeruleus. Following unilateral or bilateral homo- or heterotopic injections of the two tracers several cells of the locus coeruleus were double labeled. Combined injections of the two fluorophores in any of these forebrain areas and in the spinal cord also produced double labeled cells. The majority of double labeled cells was located in an area between the ventral and the dorsal parts of the locus coeruleus. These results indicate that individual neurons of the locus coeruleus have the possibility to influence adrenergic receptors at remote areas in the central nervous system.

Interrelations between lateral, dorsomedial and ventromedial hypothalamic nuclei in the rat. An HRP study.

Afferents of the lateral (LH) and ventromedial (VMH) hypothalamic nuclei were studied with the horseradish peroxidase method. The aim was to investigate relations between these two centers presumed to be involved in the regulation of food intake. Special attempts were made to produce HRP injections limited to intranuclear dimensions, which was achieved by iontophoretic delivery of the tracer. The results indicate that LH and VMH do not maintain direct interconnections. Both nuclei, however, appear to have numberous afferents from the dorsomedial hypothalamic nucleus (DMH) in common, which led us to extend our analysis to the DMH. DMH injections of HRP resulted in retrograde labeling of somata in both LH and VMH, suggesting a reciprocal relationship of DMH with these latter nuclei. The possible significance of such a LH-DMH-VMH relationship in the food intake control circuitry is discussed. The other labeling of afferents resulting from HRP injections localized to LH, DMH and VMH is described and discussed as regards their morphological significance. A number of these connections confirm studies using anterograde transport techniques, but others have not been described before, including an extensive projection to the VMH from the mesencephalic peripeduncular nucleus.

Bilaterally diverging axon collaterals and contralateral projections from rat locus coeruleus neurons, demonstrated by fluorescent retrograde double labeling and norepinephrine metabolism.

Evans Blue (EB) and a mixture of 4'-6'-diamidino-2-phenylindol 2 HCl and primuline (DAPI-Pr), fluorescing at different wave-lengths were injected into the rat hippocampus, frontal cortex or lateral part of the thalamus. After unilateral injection either of the two substances was retrogradely transported not only to ipsilateral but also to contralateral locus coeruleus (LC) neurons. Moreover after simultaneous injections of EB and DAPI-Pr respectively into the opposite brain structures of individual animals double-labeled neurons were observed in the bilateral LC. Unilateral electrical stimulation of the LC induced significant decreases of norepinephrine and increases of 3-methoxy-4-hydroxyphenylethylene-glycol in both the ipsi- and contralateral frontal cortex and whole forebrain, respectively. These ipsi- and contralateral alterations of the amine and its metabolite correlated highly significantly. These results indicate that several LC neurons have both contralateral and bilateral projections to the brain areas mentioned above.