Phenotypic integration in flowers of neotropical lianas: diversification of form with stasis of underlying patterns

Phenotypic integration is essential to the understanding of organismal evolution as a whole. In this study, a phylogenetic framework is used to assess phenotypic integration among the floral parts of a group of Neotropical lianas. Flowers consist of plant reproductive organs (carpels and stamens), usually surrounded by attractive whorls (petals and sepals). Thus, flower parts might be involved in different functions and developmental constraints, leading to conflicting selective forces. We found that Bignonieae flowers have very similar patterns of variance/covariance among traits and that such patterns are uncorrelated with the phylogenetic relationships between species. However, in spite of pattern stasis, our results also indicate that diversification of floral morphology in this group has occurred throughout the evolution of magnitudes of correlation among traits. Thus, we suggest that stabilizing selection has played an important role in phenotypic integration, resulting in the long-term stasis of covariance patterns underlying flower diversification during the ca. 50 Myr of evolution of Bignonieae. This is the first report of long-term stasis in the phenotypic integration of angiosperms, suggesting that patterns of floral morphology can be recognizable as specific attributes of distinct botanical families.

Composted municipal waste effects on chemical properties of a Brazilian soil

The spread of composted municipal waste (CMW) on land can be used for sustainable crop production. Nevertheless, heavy metals availability may be a problem. Therefore, the main objective of this study was to assess the impact of CMW disposal on heavy metal accumulation in soil and plants. The treatments consisted of an untreated plot (control) and four rates of CMW application. All plots were cultivated in succession of carrot, cauliflower, sweet corn, and radish. Cu and Pb significantly accumulated in the topsoil (0-5 cm) with a similar pattern in the depths of 5-10 cm and 10-20 cm. Cauliflower, for Fe and Cu, and radish, for Pb and Cu, had their tissue analysis significantly affected due to the increasing rates of application of CMW. Nevertheless, the levels of accumulation in both, soil and plant, are within permissible limits. The evidences provided by this experiment indicated that heavy metals are less likely to cause problems for the estimation of CMW loadings to Brazilian agricultural land.

Pleiotrophin disrupts calcium-dependent homophilic cell-cell adhesion and initiates an epithelial-mesenchymal transition

Regulation of the levels of tyrosine phosphorylation is essential to maintain the functions of proteins in different signaling pathways and other cellular systems, but how the steady-state levels of tyrosine phosphorylation are coordinated in different cellular systems to initiate complex cellular functions remains a formidable challenge. The receptor protein tyrosine phosphatase (RPTP)beta/zeta is a transmembrane tyrosine phosphatase whose substrates include proteins important in intracellular and transmembrane protein-signaling pathways, cytoskeletal structure, cell-cell adhesion, endocytosis, and chromatin remodeling. Pleiotrophin (PTN the protein and Ptn the gene) is a ligand for RPTPbeta/zeta; PTN inactivates RPTPbeta/zeta, leaving unchecked the continued endogenous activity of tyrosine kinases that increase phosphorylation of the substrates of RPTPbeta/zeta at sites dephosphorylated by RPTPbeta/zeta in cells not stimulated by PTN. Thus, through the regulation of the tyrosine phosphatase activity of RPTPbeta/zeta, the PTN/RPTPbeta/zeta signaling pathway coordinately regulates the levels of tyrosine phosphorylation of proteins in many cellular systems. We now demonstrate that PTN disrupts cytoskeletal protein complexes, ablates calcium-dependent homophilic cell-cell adhesion, stimulates ubiquitination and degradation of N-cadherin, reorganizes the actin cytoskeleton, and induces a morphological epithelial-mesenchymal transition (EMT) in PTN-stimulated U373 cells. The data suggest that increased tyrosine phosphorylation of the different substrates of RPTPbeta/zeta in PTN-stimulated cells alone is sufficient to coordinately stimulate the different functions needed for an EMT; it is possible that PTN initiates an EMT in cells at sites where PTN is expressed in development and in malignant cells that inappropriately express Ptn.

Positive control wells: a potential answer to remote-area quality assurance of malaria rapid diagnostic tests

Malaria rapid diagnostic tests (RDTs) are a potential breakthrough in the provision of accurate diagnosis in remote areas, but widescale use is hampered by uncertainty over accuracy under field conditions. Positive control wells, which contain recombinant malaria parasite antigen, are a novel method for addressing this need for quality assurance. The potential of a commercially available positive control well, reconstituted with blood, was assessed for use in routine monitoring of RDT sensitivity in a remote malaria-endemic region. When maintained at 4 degrees C, the wells produced a consistent level of parasite lactate dehydrogenase (pLDH) antigen activity, as detected by pLDH-detecting RDTs, but activity reduced after cumulative exposure to temperatures likely to be encountered over a few months in a malaria-endemic area. This limitation was successfully overcome in the field through centralized, controlled storage. Monitoring of RDT sensitivity was successfully incorporated into routine supervisory visits to remote clinics. However, improved temperature stability of the wells would enhance their potential. The threshold at which the wells' signal reduced RDT sensitivity requires further investigation. The wells show potential to overcome an important obstacle to the wide implementation of accurate parasite-based diagnosis and appropriate treatment. Further assessment of their place in malaria management is warranted.

Influence of carbon and nitrogen sources on Flavobacteriumgrowth and zeaxanthin biosynthesis

Growth and production of zeaxanthin by Flavobacterium sp were studied using different carbon and nitrogen sources in a chemically defined medium. The best growth was supported by sucrose, but glucose yielded similar carotenoid concentrations. Both asparagine and glutamine stimulated growth and pigment formation. Carotenoid production and glucose consumption increased as a function of asparagine concentration. In the presence of asparagine, high glucose concentrations decreased pigment production without affecting biomass formation. In the absence of glucose, asparagine could not support growth and zeaxanthin production. When compared to the effect of 55 mM glucose, 10 mM oxaloacetate increased growth and carotenoid production. Pyruvate and other intermediates of the citric acid cycle showed a similar stimulatory effect. The intermediates of glycolysis: glucose 6-phosphate and fructose 1,6-diphosphate did not support growth. These results suggest that Flavobacterium sp utilizes asparagine primarily as a nitrogen source for growth and production of zeaxanthin.

Transient colocalization of parvalbumin and calbindin D28k in the postnatal cerebral cortex: evidence for a phenotypic shift in developing nonpyramidal neurons

In the adult rat cerebral cortex the calcium-binding proteins parvalbumin and calbindin D28k are present in essentially non-overlapping populations of GABAergic interneurons. These proteins follow different developmental patterns in the cortex: calbindin D28k-immunoreactive nonpyramidal neurons are abundant until the second postnatal week and decrease markedly thereafter; it is at this time that parvalbumin immunoreactivity develops in cortical nonpyramidal neurons. To determine whether parvalbumin-immunoreactive neurons derive from calbindin D38k positive cells we used double-immunofluorescence studies for both calcium-binding proteins, together with combined immunocytochemistry for calbindin D28k and in situ hybridization for parvalbumin mRNA during postnatal development. Double-labelled cells were found in all cortical layers between P9 and P21, coinciding with the onset of parvalbumin expression. The percentage of colocalization of the two calcium-binding proteins depended on the age and layer examined. Colocalization reached a peak (80-100%) during the second postnatal week. Double-labelled neurons were rare in layer V at all ages studied. The present results indicate a phenotypic shift during the development of some cortical interneurons that halts the expression of calbindin D28k while parvalbumin expression starts. These findings agree with lineage analyses reporting that different types of nonpyramidal neuron arise from a common progenitor.

Thalamic and basal forebrain afferents modulate the development of parvalbumin and calbindin D28k immunoreactivity in the barrel cortex of the rat

In the adult barrel cortex of the rat the calcium-binding proteins calbindin D28k (CALB) and parvalbumin (PARV) are found in separate populations of GABAergic nonpyramidal neurons. In layers II to IV of the barrel cortex most PARV-immunoreactive neurons are likely to derive from a subpopulation of CALB-immunoreactive neurons whose CALB immunoreactivity ceases when they begin to express PARV between the second and third postnatal weeks. The aim of this study was to investigate the influence of subcortical afferents on the neurochemical differentiation of cortical PARV- and CALB-immunoreactive nonpyramidal neurons during development of the barrel cortex. We produced unilateral excitotoxic lesions with a single injection of ibotenic acid (0.5 microl, 0.05 M) in different subcortical nuclei in 7- to 8-day-old rats. Lesions involving the ventroposterior thalamic nuclei resulted in delayed development of PARV and CALB immunoreactivity in the barrel cortex. One week after ibotenic acid injections a transient decrease in the number of PARV-immunoreactive neurons in layer IV was observed, together with increased numbers of CALB-immunoreactive neurons in all cortical layers. The number of nonpyramidal neurons displaying coexistence of PARV and CALB in the lesioned hemisphere also increased compared with the numbers in the control hemisphere or control littermates. In contrast, lesions affecting the globus pallidus, zona incerta and reticular thalamic nucleus transiently increased the number of PARV-immunoreactive neurons in layers II and III, but had no effect on the number of CALB-positive cells. From 3 weeks onwards no differences were found between control and lesioned hemispheres after injections into either the ventroposterior thalamic nuclei or the magnocellular basal forebrain. These results suggest that CALB and PARV expression in nonpyramidal cortical neurons can be reversibly modulated in opposite directions by different cortical afferents during postnatal development.

Postnatal development of calbindin-D28k immunoreactivity in the cerebral cortex of the cat

To learn about maturational patterns of nonpyramidal neurons in the cerebral cortex, calbindin-D28k immunoreactivity was studied in the kitten cortex. Immunoreactive neurons first appear in the cortical and subcortical areas related to the limbic system, including the cingulate and retrosplenial cortices, and in the secondary motor areas. These are followed by the primary motor and sensory association areas and, finally, by the primary sensory areas. In all cortical areas, calbindin-D28k immunoreactivity first develops in layer V pyramidal neurons and later in nonpyramidal neurons, except in the primary sensory areas, where immunoreactive pyramidal neurons are not found at any age. Transient calbindin-D28k immunoreactivity occurs in pyramidal neurons that are mainly localized in the cingulate and retrosplenial cortices and in the secondary motor area, as well as in nonpyramidal neurons localized in the subplate and layer I, and in a subset of large multipolar and bitufted neurons in layer VI. Nonpyramidal neurons localized in layers II to IV, and some neurons in layer VI, develop permanent calbindin-D28k immunoreactivity. Calbindin-D28k immunoreactivity labels subsets of GABAergic interneurons that form vertical axonal tufts, so that temporal and regional patterns of calbindin-D28k immunoreactivity during development may be implicated in the maturation of columnar (vertical) inhibition in the cerebral cortex. In addition to neurons, corticofugal and afferent fibres of subcortical origin exhibit calbindin-D28k immunoreactivity. Transient calbindin-D28k immunoreactivity occurs in corticofugal fibres arising from the cingulate and prefrontal cortices, which are probably corticostriatal projection fibres. In contrast, permanent immunoreactivity occurs in what are probably thalamocortical fibres ending in layer IV, and in punctate terminals located in the upper third of layer I.

Migrating neurons in the developing cerebral cortex of the mouse send callosal axons

The presence of migrating callosal neurons during the development of the murine cerebral cortex was studied using biocytin and the lipophilic dye, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate as retrograde tracers. After injections of biocytin in the presumptive somatosensory cortex of newborn mice which were analysed one day later, many anterogradely labelled fibres coursed towards the contralateral hemisphere through the corpus callosum. Retrogradely labelled callosal cells were also observed. Most callosal neurons corresponded to immature pyramidal cells. In addition, a few biocytin-labelled callosal neurons displayed extremely fusiform shapes, vertical orientation and a short, single process emerging from the apical side of the perikaryon. At the electron microscopic level, these cells had features identical to those described for migrating callosal neurons. Twenty-four hours after birth, these migrating neurons were almost exclusively observed in the upper, dense aspect of the cortical plate (presumptive layers II-III) and only very exceptionally in the infragranular layers. No retrogradely labelled cell resembling migrating neurons were noticed after injections on postnatal days 2 or 5. To study migrating callosal neurons at embryonic stages, crystals of the lipophilic dye were injected in the corpus callosum or the contralateral white matter in embryos aged 17, 18 and 19 days, corresponding to the initial development of the corpus callosum in mice. Whereas callosal migrating neurons were not detected at embryonic days 17 and 18, injections of the lipophilic dye on embryonic day 19 revealed the presence of labelled migrating neurons in the infragranular layers. To corroborate further that these cells are migrating neurons, [3H]thymidine was administered on embryonic days 16 and 17, and labelled mice were injected with biocytin on embryonic day 19 or the first postnatal day. Retrogradely labelled callosal neurons resembling migrating neurons were autoradiographically labelled. These results indicate that the specification of certain neuronal types and the emergence of their cell type-specific characteristics occur shortly after postmitotic neurons leave the ventricular zone, before being positioned within the cortical plate.

X-ray-induced cell death in the developing hippocampal complex involves neurons and requires protein synthesis

Sprague-Dawley rats aged 1 or 15 days were irradiated with a single dose of 200 cGy X-rays and killed at different intervals from 3 to 48 hours (h). Dying cells were recognized by their shrunken and often fragmented nuclei and less damaged cytoplasm in the early stages. On the basis of immunocytochemical markers, dying cells probably represented a heterogeneous population which included neurons and immature cells. In rats aged 1 day the number of dying cells rapidly increased in the hippocampal complex with peak values 6 h after irradiation. This was followed by a gentle decrease to reach normal values 48 h after irradiation. The most severely affected regions were the subplate and the cellular layer of the subiculum, gyrus dentatus and hilus, and the stratum oriens and pyramidale of the hippocampus (CA1 more affected than CA2, and this more affected than CA3). X-ray-induced cell death was abolished with an injection of cycloheximide (2 micrograms/g i.p.) given at the time of irradiation. X-ray-induced cell death was not changed after the intraventricular administration of nerve growth factor (NGF; 10 micrograms in saline) at the time of irradiation. Cell death was not induced by X-irradiation in rats aged 15 days. These results indicate that X-ray-induced cell death in the hippocampal complex of the developing rat is subjected to determinate temporal and regional patterns of vulnerability; it is an active process mediated by protein synthesis but probably not dependent on NGF.

Late appearance of parvalbumin-immunoreactive neurons in the rodent cerebral cortex does not follow an 'inside-out' sequence

Parvalbumin (PARV), a Ca(2+)-binding protein believed to play a role in neuronal excitability, is contained in certain GABAergic inhibitory neurons of the cerebral cortex. Here we report that expression of PARV in the developing neocortex of rats and mice occurs with a sequence which does not follow the usual 'inside-out' gradient of cortical development. Thus, PARV-immunoreactive neurons appear first in layer V and only thereafter in the remaining cortical layers. An adult-like pattern of immunoreactivity is reached simultaneously in layers II-III and VIb. These observations indicate that the mechanisms regulating the functional maturation of PARV-containing inhibitory neurons are different from those that generally govern developmental processes in the cortex.

Parvalbumin and calbindin immunoreactivity in the cerebral cortex of the hedgehog (Erinaceus europaeus)

To investigate the morphology and distribution of nonpyramidal neurons in the brain of insectivores, parvalbumin and calbindin 28 kDa immunoreactivity was examined in the cerebral cortex of the hedgehog (Erinaceus europaeus). Parvalbumin-immunoreactive cells were found in all layers of the isocortex, but in contrast to other mammals, a laminar organisation or specific regional distribution was not seen. Characteristic parvalbumin-immunoreactive neurons were multipolar cells with large ascending and descending dendrites extending throughout several layers. Calbindin-immunoreactive neurons were similar to those found in other species, although appearing in smaller numbers than in the cerebral cortex of more advanced mammals. The morphology and distribution of parvalbumin- and calbindin-immunoreactive cells in the piriform and entorhinal cortices were similar in hedgehogs and rodents. Parvalbumin-immunoreactive cells in the hippocampal complex were pyramidal-like and bitufted neurons, which were mainly found in the stratum oriens and stratum pyramidale of the hippocampus, and in the stratum moleculare and hilus of the fascia dentata. Heavily stained cells were found in the deep part of the stratum granulare. Intense calbindin immunoreactivity occurred mainly in the granule cell and molecular layers of the dentate gyrus and in the mossy fibre layer. The most outstanding feature in the hippocampal complex of the hedgehog was the extension of calbindin immunoreactivity to CA1 field of the hippocampus, suggesting, in agreement with other reports, that mossy fibres can establish synaptic contacts throughout the pyramidal cell layer.