Vertical migration and feeding of Euphausia lucens (Euphausiacea) in the Southern Benguela

Diel migration and feeding were examined for populations ofEuphausia lucens living in the near- and offshore waters ofthe southern Benguela. Euphausiids at both stations displayednocturnal diel vertical migration patterns. Animals inshoreascended in a slow-fast-slow manner which seems to be relatedto differential food concentrations throughout the water columnPronounced quantitative and qualitative changes in the dietof E.lucens were observed offshore but not inshore. These differencesare discussed in relation to different ambient food environments     

Plant dispersal strategies and the colonization of Araucaria forest patches in a grassland‐forest mosaic

Questions: In a natural grassland‐forest mosaic: What is the influence of phylogeny and diaspore traits related to disperser attraction (DAT) on (1) seed size/number trade‐off (SSNT) in woody species colonizing forest patches; (2) on the frequency of the species? 3. What is the influence of forest patch area on mean seed size and number. 4. Do phylogeny and DAT expressed at the species level affect this relationship? Location: Campos grassland and Araucaria forest in São Francisco de Paula, RS, Brazil, at ca. 29°28’ S; 50° 13’ W. Methods: Forest patches of different sizes in a grassland site recovering for ten years since human disturbances were surveyed by the relative abundance of vertebrate‐dispersed woody saplings. We described colonizer species according to taxonomic phylogenetic relationships and diaspore type, size and color. We analyzed with a variation partitioning method their influence on SSNT and on species frequency in the patches. At the community level we regressed mean seed size and number on forest patch area and evaluated how these relationships were affected by phylogeny and DAT at the species level. Results: 1. Phylogeny and DAT mostly explained seed size and seed number per diaspore variation. 2. By controlling phylogeny and DAT influence the frequency of species in forest patches was positively associated with their seed number in the diaspores, and negatively associated with their seed size. 3. Mean seed size and seed number at the community level were positively associated with patch area. 4. When phylogeny and DAT influences on seed size were removed this relationship was stronger for seed size and weaker for seed number. Conclusions: 1. Energy allocation to dispersal in detriment of offspring survival increased the successful establishment of colonizer species in forest patches, despite phylogenetic relationships and DAT variation in their diaspores. 2. Although patch area exerted a selective pressure on seed size, habitat preferences of dispersers may also influence patch colonization.     

Isolation and nucleotide sequence of the ribosomal protein S16-encoding gene from Aspergillus nidulans.

A genomic clone has been isolated from Aspergillus nidulans which is homologous to the ribosomal (r) protein S16-encoding gene of Saccharomyces cerevisiae (S16A) and the r-protein S19-encoding gene of rat (S19). The amino acid (aa) sequences, deduced from nucleotide (nt) sequence analysis, show that in both cases more than 63% of the aa are conserved. The proposed A. nidulans r-protein S16 gene (rps16) differs from that of S. cerevisiae in that it occurs as a single copy in the haploid genome (rather than two copies as in yeast) and contains two putative introns (rather than one). The mRNA leader is long compared to many Aspergillus genes, commencing 293 nt upstream from the coding region, and contains an open reading frame of 13 codons.     

Oxidative stress response induced in rat primary hepatocyte monolayers by mechanical removal of adherent cells

We show that mechanical separation of adherent rat primary hepatocytes after the monolayer-forming stage causes the induction of the oxidative stress genes HO-1 (haem oxygenase) and MnSOD (manganese superoxide dismutase). The procedures for enzymatically breaking up liver tissue structure and isolating hepatocytes do not cause HO-1 and MnSOD activation. Only after a 3-h incubation, during which hepatocytes form a monolayer on culture dishes, does the hydrodynamic shearing away of necrotic cells sticking to the monolayer surface activate these two genes. Analysis of this injury-response pathway shows that oxidative stress and mitochondrial dysfunction play a role, as activation can be repressed by antioxidants and by respiratory inhibitors. Recovery of the cells takes a further 24-h incubation during which HO-1 and MnSOD expression returns to basal levels.