Tidal flushing of ammonium from intertidal sediments of Ria Formosa,Portugal

Ammonium concentrations were determined in near-bottom water and intertidal surface sediments collected in February and July 1993 at five stations of Ria Formosa, a shallow meso-tidal coastal lagoon in southern Portugal. At each station, samples were taken a few minutes before tidal inundation, and subsequently 2, 10, 15 and 20 minutes thereafter. Ammonium concentration in near-bottom waters increased dramatically in the first 2 minutes followed by a decrease during the 18 minutes of flooding (maximum range 10.3-2.2 M). The highest levels in the flooding water were concomitant with a decrease of extractable ammonium recorded in the upper sediment layer (2 cm). Laboratory experiments indicated that ammonium is easily extracted from the sediment solids by physical perturbation, as one would expect when tidal water flushes over the intertidal area. This perturbation results in the export of ammonium from the sediment, by pulse mechanisms of short time intervals. On a daily scale this amount is two orders of magnitude higher than transport resulting from molecular diffusion.     

Effect of ethanol and fatty acids on malolactic activity ofLeuconostoc oenos

Medium-chain fatty acids (C₆ to C₁₂), produced by yeast metabolism during alcoholic fermentation, are known to be inhibitory to lactic acid bacteria. The purpose of this work was to clarify the effect of both ethanol and decanoic and dodecanoic acids on the growth and malolactic activity of aLeuconostoc oenos strain isolated from Portuguese red wine. Ethanol in concentrations up to 12% had no significant effect on malolactic activity but strongly inhibited cell growth. The fatty acids decanoic acid, in concentrations up to 12.5 mg l^–1, and, dodecanoic acid up to 2.5 mg l^–1 seemed to act as growth factors stimulating also malolactic activity; at higher concentrations they exerted an inhibitory effect. We found clear pH dependence between pH 3.0 and pH 6.0, between decanoic acid concentration and its effect on malolactic activity, indicating that the undissociated molecule is the active form. At pH 3.0 the results can be explained by considering that fatty acids enter the cell as protonated molecules and dissociate in the cytoplasm due to the higher internal pH, leading to increased intracellular hydrogenous concentration. This may be the basis of two different effects that contribute to the observed inhibition: decrease in the intracellular pH and dissipation of the transmembrane proton gradient, thus inhibiting intracellular enzymes and ApH-dependent transport systems.     

Basement membrane components of bronchial epithelium in humans suffering from chronic nonspecific lung diseases

Collagen IV and laminin are important constituents of the basement membrane (BM). By use of immunocytochemistry we examined the occurrence and distribution of these two components in the BM beneath normal, mucoid and metaplastic epithelium of large bronchi in 22 adults suffering from chronic nonspecific lung diseases. Both collagen IV and laminin were expressed as a thin and continuous layer beneath the epithelium in most tissue specimens with normal epithelium. In a few specimens the layer showed interruptions with a patchy distribution of the immunoreactivity. Three patterns of distribution of BM components were found under the metaplastic epithelium. Total absence of immunoreactive collagen IV and laminin was the most common variant. Weak and scarce staining for both proteins in the BM characterized the second pattern. The third variant showed strong collagen IV immunoreactivity but lack of laminin. The BM beneath the mucoid epithelium was characterized by irregular distribution of collagen IV and laminin. We suggest that the occurrence and distributional pattern of the BM components are related to the type of overlying epithelium and connected with an altered synthesis of these components.     

A mating-type factors of Coprinus cinereus have variable numbers of specificity genes encoding two classes of homeodomain proteins

We have identified the seven genes that constitute the A43 mating-type factor of Coprinus cinereus and compare the organisation of A43 with the previously characterised A42 factor. In both, the genes that trigger clamp cell development, the so-called specificity genes, are separated into and loci by 7 kb of noncoding sequence and are flanked by homologous genes -fg and -fg. The specificity genes are known to encode two classes of dissimilar homeodomain (HD1 and HD2) proteins and have different allelic forms which show little or no cross-hybridisation. By partial sequencing we identified a divergently transcribed HD1 (a1-2) and HD2 (a2-2) gene in the A43 locus. a2-2 failed to elicit clamp cell development in three different hosts, suggesting that it is non-functional. a1-2 elicited clamp cells in an A42 host that has only an HD2 gene (a2-1) in its locus, thus demonstrating that the compatible A mating interaction is between an HD1 and an HD2 protein. The A43 locus contains three specificity genes, the divergently transcribed HD1 and HD2 genes b1-2 and b2-2 and a third HD1 gene (d1-1) that was shown by hybridisation and transformation analyses to be functionally equivalent to d1-1 in A42. An untranscribed footprint of a third A42 HD1 gene, c1-1, was detected between the A43 b2-2 and d1-1 genes by Southern hybridisation.     

Large DNA inversions,deletions, and TaqI site mutations in severe haemophilia A

Large DNA inversions caused by an intrachromosomal recombination between homologous regions located in intron 22 and 5 of the factor VIII gene have recently been identified in patients with severe haemophilia A. To evaluate better the prevalence of this large inversion and to estimate the overall sensitivity of the Southern blot/hybridization method we analysed the factor VIII gene of 49 unrelated patients with severe haemophilia A. All patients were screened for the inversion mutation, TaqI site mutations, and deletions. Mutations were identified in 31 (63%) patients, and comprised 24 large inversions, 4 partial deletions, and 3 point mutations. Three different haplotypes were characterised in the patients presenting the inversion mutation, confirming its independent origin. Two novel deletions are reported: a large one spanning from intron 14 to intron 22 and a deletion of 86 bp comprising the 3 region of exon 1 and 39–41 bp of intron 1. DNA sequencing of the deletion junction showed no significant homology between normal 5 and 3 sequences around the breakpoints. A novel missense mutation is also reported: CGAGGA, Arg-2209 to Gly. These results confirm that the inversion mutation is the most common cause of severe haemophilia A and indicate that the Southern blot/hybridization assay should be used as the first method for screening of mutations in severe haemophilia A.     

Inspection and evaluation of host plant by the butterfly Mechanitis lysimnia (Nymph., Ithomiinae) before laying eggs: a mechanism to reduce intraspecific competition

Parasites of all kinds affect the behaviour of their hosts, often making them more susceptible to predators. The associated loss in expected future reproductive success of infected hosts will vary among individuals, with younger ones having more lose than older ones. For this reason, young hosts would benefit more by opposing the effects of parasites than old ones. In a laboratory study, the effects of the trematode Telogaster opisthorchis on the anti-predator responses of the upland bully (Gobiomorphus breviceps) and of the common river galaxias (Galaxias vulgaris) were examined in relation to fish age. In a bully population where parasites were very abundant, the magnitude of the fish's anti-predator responses decreased as the number of parasites per fish increased, and this effect was significantly more pronounced in age 2 + and, to a lesser extent, age 3 + fish than in age 1 + fish. In another bully population where parasites were 10 times less abundant, similar effects were noticeable but not significant, whereas no effects of parasites on the responses of galaxiids to predators were apparent. Differences in the abundance of parasites and in their sites of infection in fish may explain the variability among host populations or species. However, in the bully population with high parasite abundance, parasitism has age-dependent effects on responses to predators, providing some support for the prediction that young fish with high expected future reproductive success invest more energy into opposing the effects of parasites than do older fish.     

Biology and myriapod egg predation by the Neotropical myrmicine antStegomyrmex vizottoi (Hymenoptera: Formicidae)

Summary For the first time for a Neotropical ant and for Myrmicinae, the searching behavior and specialized predation of spirobolid millipede eggs byStegomyrmex vizottoi Diniz will be described. The relationship between morphology and habits is studied, as are nest architecture and distribution of the ant population in the nest chambers. We also report on some observations of behavior in the field and laboratory.We dedicate this paper to William L. Brown Junior, on the occasion of his 70^th birthday.     

Update on proliferation-associated antibodies applicable to formalin-fixed paraffin-embedded tissue and their clinical applications

Summary This review provides an update on proliferation-associated antibodies applicable to immunohistochemical techniques in formalin-fixed paraffin-embedded tissue. New insights into proliferating cell nuclear antigen (PCNA) and antibodies to PCNA are presented. The characterization of the protein recognized by the Ki-67 antibody has enabled production of a new range of antibodies (monoclonal and polyclonal) which have immunostaining profiles similar to those of the original antibody. A new proliferation-associated antibody, KiS1, is described. The clinical applications of antibodies to PCNA in human material are summarized, and the limitations of these studies are discussed.     

Ethnobotany of Atlantic Forest coastal communities: Diversity of plant uses in Gamboa (Itacuruçá island,Brazil)

Local plants are a very important resource for the community of Gamboa, located at Itacuruçá Island, Sepetiba Bay, State of Rio de Janeiro, Brazil Ninety species of plants, belonging to 40 families, are used for a variety of purposes, such as food, construction, handicraft, and medicine. In a survey medicinal uses for plants were the most quoted by the community. Uses of medicinal plants within Gamboa and with other coastal communities are analyzed using diversity indices. Use by different categories of people based on sex, age, and economic activity was compared and significant differences were found among the groups compared, except for economic categories (fishermen and non-fishermen). The theory of island biogeography is shown to be useful for analyzing different levels of resource uses on different islands.     

Cryptophytes: An emerging algal group in the rapidly changing Antarctic Peninsula marine environments

The western Antarctic Peninsula (WAP) is a climatically sensitive region where foundational changes at the basis of the food web have been recorded; cryptophytes are gradually outgrowing diatoms together with a decreased size spectrum of the phytoplankton community. Based on a 11-year (2008–2018) in-situ dataset, we demonstrate a strong coupling between biomass accumulation of cryptophytes, summer upper ocean stability, and the mixed layer depth. Our results shed light on the environmental conditions favoring the cryptophyte success in coastal regions of the WAP, especially during situations of shallower mixed layers associated with lower diatom biomass, which evidences a clear competition or niche segregation between diatoms and cryptophytes. We also unravel the cryptophyte photo-physiological niche by exploring its capacity to thrive under high light stress normally found in confined stratified upper layers. Such conditions are becoming more frequent in the Antarctic coastal waters and will likely have significant future implications at various levels of the marine food web. The competitive advantage of cryptophytes in environments with significant light level fluctuations was supported by laboratory experiments that revealed a high flexibility of cryptophytes to grow in different light conditions driven by a fast photo-regulating response. All tested physiological parameters support the hypothesis that cryptophytes are highly flexible regarding their growing light conditions and extremely efficient in rapidly photo-regulating changes to environmental light levels. This plasticity would give them a competitive advantage in exploiting an ecological niche where light levels fluctuate quickly. These findings provide new insights on niche separation between diatoms and cryptophytes, which is vital for a thorough understanding of the WAP marine ecosystem.