Phytoplankton equilibrium phases during thermal stratification in a deep subtropical reservoir

1. Equilibrium and non-equilibrium hypotheses have often been used to explain observations in community ecology. Published case studies have demonstrated that steady state phytoplankton assemblages are more likely to occur in deep lakes than in shallow mixed ones.
2. Phytoplankton seasonal succession was studied by weekly sampling in Faxinal Reservoir (S Brazil), a subtropical deep, clear, warm monomictic and slightly eutrophic reservoir. This study demonstrated an alternation of steady and non-steady state phases of phytoplankton assemblages with different dominant species during the steady states.
3. During the studied period, three steady states were identified with different dominant algal species: Anabaena crassa (Cyanobacteria), Nephrocytium sp. (green algae) and Asterionella (diatoms).
4. Each steady state in Faxinal Reservoir developed under stratified conditions of the water column according to the predictions of the disturbance concepts. Apparently, the major forces driving the development and persistence of these steady-state phases were closely related to thermal stratification and its consequences.
5. This study is the first report on development of more than one steady state within a year in a stratified water body. The development of three steady states might be the result of the relatively long stratification period in the Faxinal Reservoir and to its unique geochemical features.     

Non-secretory solitary plasmacytoma of the spleen

A case of primary nonsecretory plasmacytoma of the spleen is reported. On laparotomy and splenectomy a 920 g spleen was removed, measuring 16×14×6 cm. The cut surface of the entire spleen showed that the tumour occupied most of the splenic tissue. A bone marrow aspirate and trephine, skeletal survey showed no signs of myeloma. Biopsy of the liver and regional lymph nodes was normal. Immunocytochemistry of the splenic tumour showed positivity for pan-B and plasma cell markers. After splenectomy the patient was treated with chemotherapy according to protocol VBCMP (M2).     

Beta-Oxidation in Glyoxysomes from Euglena*

SYNOPSIS. We demonstrated previously the presence of glyoxysomes containing the glyoxylate cycle enzymes in Euglena gracilis grown in the dark on ethanol. We have now established that the glyoxysomes of Euglena grown on hexanoate also contain the following enzymes of the pathway for β-oxidation of fatty acids: hexanoyl-CoA synthetase, 3-β-hydroxyacyl-CoA dehydrogenase and thiolase. Estimations of specific activities indicate that these enzymes are over 20 times as active in glyoxysomes as they are in mitochondria, suggesting that the β-oxidation of fatty acids occurs almost entirely in Euglena glyoxysomes under these conditions. Thus, the entire portion of the gluconeogenic pathway from fatty acid to succinate is localized in the glyoxysome of Euglena.