Monstrilloida (Copepoda) off the Brazilian coast

Seven monstrilloid species of the genera Thaumaleus and Monstrilla (Copepoda) are reported from the Brazilian coast. Occurrence, distribution and ecological information is given for: T. longispinosum, T. rigidum, T. quadridens, M. recticulata, M. grandis, M. dubia and M. rugosa.     

Fusion and histocompatibility in Rhodophyta

Fully developed thalli of Chondrus crispus, Gracilaria chilensis, Gymnogongrus furcellatus and Mazzaella laminarioides were used to assess tissue compatibility. The effect of thallus polarity on grafting and regeneration was also evaluated. Fusion did occur between fragments of the same life history phase in C. crispus, G. chilensis, G. furcellatus and M. laminarioides. Fusion between sporophytic and gametophytic tissue occurred in C. crispus, G. chilensis and M. laminarioides. Intergeneric fusion was observed between C. crispus and M. laminarioides, but not between G. chilensis and G. furcellatus.Outer cell wall, cortex and medulla were continuous at the contact face in compatible combinations. Medullary cells in the attached fragments were thinner and longer than normal cells, forming an interwoven scar plate. Thallus polarity did not modify fusion and regeneration.     

Communication in the migratory termite-hunting ant Pachycondyla (= Termitopone) marginata (Formicidae, Ponerinae)

The Neotropical species Pachycondyla marginata conducts well-organized predatory raids on the termite species Neocapritermes opacus and frequently emigrates to new nest sites. During both activities the ants employ chemical trail communication. The trail pheromone orginates from the pygidial gland. Among the substances identified in the pygidial gland secretions, only citronellal was effective as a trail pheromone. Isopulegol elicited an increase in locomotory activity in the ants and may function as a synergist recruitment signal. The chemical signal is enhanced by a shaking display performed by the recruiting ant.     

Deep soil heterogeneity and fine root distribution in forests and pastures of eastern Amazonia

Little is known about deep soil heterogeneity, or its relationship with fine root distribution. Beneath a mature, closed-canopy forest of eastern Amazonia, and the pastures and secondary forests that are derived from this forest, soil soft spots and hollow chambers occur to at least 9 meters depth. We measured the vertical distribution of these soil patches, and compared chemical characteristics, mycorrhizal infection, and root density of soil soft spots with the surrounding matrix of more homogeneous soil. Soil soft spots and chambers varied little with depth, but occupied the greatest soil volume (0.8 to 1.2%) from 4 to 6 m depth in the mature forest. Soft spots had lower pH, P availability and arbuscular mycorrhizal infection, and higher K availability than surrounding soil. Root length density was 2 to 15 times higher in soft spots than in surrounding soil. In the pastures, roots were found only in soil soft spots at depths of >3 m. Pastures and secondary forest had more soil chambers in the upper meter of soil than mature forest, but were otherwise indistinguishable in their patterns of deep soil heterogeneity. Soil soft spots may be vestiges of cutter ant nest chambers, while hollow chambers are cutter ant chambers and root channels. Chambers may act as conduits for root penetration and water penetration to deep soil.Abbreviations AM arbuscular mycorrhizae - RLD root length density (root length per unit of soil volume)     

Large scale patterns and trophic structure of southern African rocky shores: the roles of geographic variation and wave exposure

In this study we revise the biogeographic delimitation, and large-scale patterns of community structure of the intertidal rocky shores of southern Africa. We use binary (presence/absence) and per-species biomass data collected at fifteen localities and thirty-seven different rocky sites, encompassing the shores of southern Namibia, South Africa and southern Mozambique. Multivariate analyses revealed that the shores of southern Africa (south of 25°) can be divided into three main biogeographic provinces: the west coast or Namaqua province, the south coast or Agulhas province and the east coast or Natal province. The biomass structure of the intertidal rocky shores communities of southern Africa varied at a large scale, corresponding to biogeographic differences, while local-scale variation accorded with the intensity of local wave action. The average biomass of west coast communities was on average significantly greater than that of the south and east provinces. At a local scale, the community biomass on exposed shores was an order of magnitude greater than on sheltered shores, within all biogeographic provinces. Semi-exposed shores exhibited intermediate average biomass. The trophic structure of these communities varied significantly with wave action: autotrophs, filter-feeders and invertebrate predators were more prevalent on wave exposed than sheltered shores, whereas grazers were more abundant on sheltered and semi-exposed shores. Exposed shores were consistently dominated by far fewer species than semi-exposed and sheltered shores, independently of biogeographic differences. Within all biogeographic provinces semi-exposed and sheltered shores were more diverse than exposed shores. West coast intertidal communities therefore had high levels of biomass, but were consistently species-poor. Several working hypotheses that could explain these large and small-scale patterns are presented.     

Purification and characterization of the high molecular weight microtubule associated proteins from neonatal rat brain

The changes in the levels of microtubule-associated proteins (MAPs) during advanced embryonic stages, neonatal and adult organisms reflect the importance of these cytoskeletal proteins in relation to the morphogenesis of the central nervous system. MAP-1B is found in prenatal brains and it appears to have the highests levels in neonatal rat brains, being a developmentally-regulated protein. In this research, a fast procedure to isolate MAP-1B, as well as MAP-2 and MAP-3 from neonatal rat brains was designed, based on the differential capacity of poly L-aspartic acid to release MAPs during temperature-dependent cycles of microtubule assembly in the absence of taxol. The high molecular weight MAP-1B was recovered in the warm supernatants after microtubular protein polymerization in the presence of low concentrations of polyaspartic acid. Instead, MAP-2 and a 180 kDa protein with characteristics of MAP-3 remained associated to the polymer after the assembly. Further purification of MAP-1B was attained after phosphocellulose chromatography. Isolation of MAP-2 isoforms together with MAP-3 was achieved on the basis of their selective interactions with calmodulin-agarose affinity columns. In addition, MAP-2 and MAP-3 were also purified on the basis of their capacities to interact with the tubulin peptide -II (422–434) derivatized on an Affigel matrix. However, MAP-1B did not interact with the -II tubulin fragment, but it showed interaction with the Affigel-conjugated -I (431–444) tubulin peptide. The different MAPs componentes were characterized by western blots using specific monoclonal antibodies. A salient feature of neonatal rat brain MAP-3 was its interactions with site-directed antibodies that recognize binding epitopes on the repetitive sequences of tau and MAP-2. However, these site-specific antibodies did not interact with MAP-1B from the neonatal rat brain tissue.Abbreviations PAA poly (L-aspartic acid) - HMW-MAPs high molecular weight microtubule associated proteins     

Excitatory and Inhibitory Effects of A1 and A2A Adenosine Receptor Activation on the Electrically Evoked [3H]Acetylcholine Release from Different Areas of the Rat Hippocampus

Abstract: The modulation by adenosine analogues and endogenous adenosine of the electrically evoked release of [³H]acetylcholine ([³H]ACh) was compared in subslices of the three areas of the rat hippocampus (CA1, CA3, and dentate gyrus). The mixed A₁/A₂ agonist 2-chloroadenosine (CADO; 2–10 µM) inhibited, in a concentration-dependent manner, the release of [³H]ACh from the three hippocampal areas, being more potent in the CA1 and CA3 areas than in the dentate gyrus. The inhibitory effect of CADO (5 µM) on [³H]ACh release was prevented by the A₁ antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 50 nM) in the three hippocampal areas and was converted in an excitatory effect in the CA3 and dentate gyrus areas. The A_2A agonist CGS-21680 (30 nM) produced a greater increase of the evoked release of [³H]ACh in the CA3 than in the dentate gyrus areas, whereas no consistent effect was found in the CA1 area or in the whole hippocampal slice. The excitatory effect of CGS-21680 (30 nM) in the CA3 area was prevented by the adenosine receptor antagonist 3,7-dimethyl-1-propargylxanthine (10 µM). Both adenosine deaminase (2 U/ml) and DPCPX (250 nM) increased the evoked release of [³H]ACh in the CA1 and CA3 areas but not in the dentate gyrus. The amplitude of the effect of DPCPX and adenosine deaminase was similar in the CA1 area, but in the CA3 area DPCPX produced a greater effect than adenosine deaminase. It is concluded that the electrically evoked release of [³H]ACh in the three areas of the rat hippocampus can be differentially modulated by adenosine. In the CA1 area, only A₁ inhibitory receptors modulate ACh release, whereas in the CA3 area, both A_2A excitatory and A₁ inhibitory adenosine receptors modulate ACh release. In the dentate gyrus, both A₁ inhibitory and A_2A excitatory adenosine receptors are present, but endogenous adenosine does not activate them.     

Changes in populations of soil microorganisms,nematodes, and enzyme activity associated with application of powdered pine bark

Evaluation of enzyme activities in combination with taxonomic analyses may help define the mechanisms involved in microbial decomposition of orgaic amendments and biological control of soilborne pathogens. In this study, powdered pine bark was added to nematode-infested soil at rates of 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 g kg^–1. Total fungal populations did not differ among treatments immediately after application of pine bark. After 7 days, fungal populations were positively correlated with increasing levels of pine bark. This increase was sustained through 14 and 21 days.Penicillium chrysogenum andPaecilomves variotii were the predominant fungal species isolated from soil amended with pine bark. Total bacterial populations did not change with addition of pine bark at 0, 7, and 14 days after treatment. At 21 and 63 days, total bacterial populations declined in soil receiving the highest rates of pine bark. Addition of pine bark powder to soil caused a shift in predominant bacterial genera fromBacillus spp. in nonamended soil, toPseudomonas spp. in amended soil. Soil enzyme activities were positively correlated with pine bark rate at all sampling times. Trehalase activity was positively correlated with total fungal populations and with predominant fungal species, but was not related to bacterial populations. The number of non-parasitic (non-stylet bearing) nematodes andMeloidogyne arenaria in soil and roots were not correlated with pine bark rate. However,Heterodera glycines juveniles in roots, and the number of cysts g^–1 root, declined with increasing levels of pine bark.Journal Series Series No. 18-933598 Alabama Agricultural Experiment Station     

Accumulation of UV-absorbing flavonoids induced by UV-B radiation inAmbidopsis thaliana L.

Irradiation ofArabidopsis with ultraviolet (UV) light resulted in intensity- and wavelength-dependent increases in the levels of a small family of UV-absorbing flavonoids, which accumulate in the aerial parts of the plants. A gradient of sensitivity to UV-B radiation is described in the different leaves of developingArabidopsis plants whereby the earliest formed leaves become damaged by UV-B faster and more extensively than later formed leaves. This UV-sensitivity gradient tightly parallels differences in constitutive as well as UV-induced levels of flavonoid accumulation among the various leaves, suggesting a direct role of flavonoids in protection against damage by UV radiation. The level of accumulated flavonoids, both constitutive and UV-induced, in each leaf appear to be dependent on the specific developmental state of each leaf as well as the overall developmental state of the plant. The UV-mediated flavonoid response, along with the observed UV-induced damage, appear not to be systemic inArabidopsis but restricted very closely to the irradiated areas of leaves.I am deeply indebted to Robert Fischer and Bob Buchanan for providing access to their laboratories and for their invaluable help without which this work could not have been realized. I especially wish to thank Lola Peñarrubia, Elena del Campillo, Patrick Neil and Julie Montgomery for innumerable and fruitful discussions. This work was supported by Cooperative State Research Service, U.S. Department of Agriculture, under Agreements Nos. 90-37280-5664 and 90-372780-5808.