Stoichiometry of aerobic mineralization (O/C) of aquatic macrophytes leachate from a tropical lagoon (São Paulo –Brazil)

The temporal variation of stoichiometry between consumed oxygen and oxidized carbon was investigated for the aerobic mineralization of leachates from aquatic macrophytes. Seven species of aquatic plants, viz. Cabomba piauhyensis, Cyperus giganteus, Egeria najas, Eichhornia azurea, Salvinia auriculata, Scirpus cubensisand Utricularia breviscapa, were collected from Òleo lagoon located in the floodplain of Mogi-Guacu river (São Paulo State, Brazil). After being collected, the plants were washed, oven-dried and triturated. In order to obtain the leachate, the fragments were submitted to an aqueous extraction (cold). Mineralization chambers were incubated at 20 °C containing leachates dissolved in water samples from Òleo lagoon to a final concentration of ca. 200 mg l^–1on carbon basis. The chambers were maintained under aerobic conditions; the concentrations of the organic carbon (particulate and dissolved) and the dissolved oxygen were measured during approximately 80 days. Elemental analysis of the detritus and the concentrations of the remaining material (DOC and POC) were used to determine the amounts of mineralized organic carbon. The data were analyzed with first-order kinetics models, from which the daily rates of consumption (carbon and oxygen) and the stoichiometry (O/C) were determined. In the early phase of mineralization the O/C rates increased before reaching a maximum, after which they tended to decrease. For the mineralization of leachates from C. giganteus, S. auriculata and U. breviscapa, the decrease was relatively slow. For all substrata the initial values were smaller than 1, and ranged from 0.42 (S. cubensis) to 0.81 (C. piauhyensis). The maximum values were within the range from 0.58 (U. breviscapa) to 23.1 (E. najas) and at their highest 26th (C. piauhyensis) and 106th (C. giganteus) days. These variations are believed to be associated with the chemical composition of the leachates, with their transformations and alterations of metabolic pathways involved in the mineralization.     

A New Real-Time PCR for the Detection of Plasmodium ovale wallikeri

It has been proposed that ovale malaria in humans is caused by two closely related but distinct species of malaria parasites: P. ovale curtisi and P. ovale wallikeri. We have extended and optimized a Real-time PCR assay targeting the parasite’s small subunit ribosomal RNA (ssrRNA) gene to detect both these species. When the assay was applied to 31 archival blood samples from patients diagnosed with P. ovale, it was found that the infection in 20 was due to P. ovale curtisi and in the remaining 11 to P. ovale wallikeri. Thus, this assay provides a useful tool that can be applied to epidemiological investigations of the two newly recognized distinct P. ovale species, that might reveal if these species also differ in their clinical manifestation, drugs susceptibility and relapse periodicity. The results presented confirm that P. ovale wallikeri is not confined to Southeast Asia, since the majority of the patients analyzed in this study had acquired their P. ovale infection in African countries, mostly situated in West Africa.     

Red blood cells as an antigen-delivery system.

The use of adjuvants is usually required to induce strong immunological responses to protein antigens. However, in many cases these adjuvants cannot be extensively applied in human and veterinary vaccinations because of associated inflammatory reactions or granuloma formation. We show here that protein antigens (bovine serum albumin, hog liver uricase, and yeast hexokinase), coupled to autologous red blood cells by way of a biotin-avidin-biotin bridge, elicit an immunological response in mice similar to or higher than that obtained by the use of Freund's adjuvant. Quantities as low as 0.5 micrograms/mouse are high enough to generate these immunological responses. Furthermore, splenocytes of mice immunized by red blood cell-coupled antigens can be used to generate hybridomas secreting monoclonal antibodies. Thus, the delivery of antigens by autologous red blood cells is an effective way to avoid the use of adjuvants for producing anti-peptide antibodies and possibly to generate peptide vaccines.     

Errors Related to Different Techniques of Intraperitoneal Injection in Mice

We found a 12% error in the placement of intraperitoneal injections of mice with the one-man procedure of injection. With a two-man procedure, the incidence of error was consistently reduced to 1.2%.     

Hypotonic swelling-induced Ca2+ release by an IP3-insensitive Ca2+ store

Hypotonicswelling increases the intracellular Ca²⁺ concentration([Ca²⁺]_i) in vascular smooth muscle cells(VSMC). The source of this Ca²⁺ is not clear. To study thesource of increase in [Ca²⁺]_i in response tohypotonic swelling, we measured [Ca²⁺]_i infura 2-loaded cultured VSMC (A7r5 cells). Hypotonic swelling produced a40.7-nM increase in [Ca²⁺]_i that was notinhibited by EGTA but was inhibited by 1 µM thapsigargin. Priordepletion of inositol 1,4,5-trisphosphate (IP₃)-sensitive Ca²⁺ stores with vasopressin did not inhibit the increasein [Ca²⁺]_i in response to hypotonic swelling.Exposure of ⁴⁵Ca²⁺-loaded intracellular storesto hypotonic swelling in permeabilized VSMC produced an increase in⁴⁵Ca²⁺ efflux, which was inhibited by 1 µMthapsigargin but not by 50 µg/ml heparin, 50 µM ruthenium red, or25 µM thio-NADP. Thus hypotonic swelling of VSMC causes a release ofCa²⁺ from the intracellular stores from a novel sitedistinct from the IP₃-, ryanodine-, and nicotinic acidadenine dinucleotide phosphate-sensitive stores.

     

Avidity analysis of the human immune response to a chitin binding protein of Toxoplasma gondii.

A 30-33 kDa electroeluted fraction of T. gondii tachyzoites improved discrimination between acute and chronic phase sera when used instead of the whole tachyzoite extract in an avidity-ELISA. In order to identify the components of these fractions, crude tachyzoite antigen was fractionated by anionic exchange chromatography. The 30-33 kDa antigen cluster eluted in the not-bound fraction could account for a large proportion of the antibody response against the 30-33 kDa electroeluted fraction. According to the N-terminal sequence data, this antigen fraction is composed mainly of SAG1 and another protein with high homology to chitin binding proteins from plants.     

A study of the histology and morphology of the digestive tract of the sea-bream, Sparus aurata

The anatomy and the histology of the digestive tract of young and adult sea-bream is described from studies using light and scanning electron microscopy. The dentition in the juvenile (25–30 mm long) comprises all canine-like teeth, to which plate teeth and transition elements are added in the adult.
The oesophagus shows a multi-layered mucosa in the upper part, and single-layered regions in the lower part. The multi-layered regions are formed by epithelial cells, mucus-secreting cells and by cells rich with eosinophilic granules.
The Y-shaped stomach, clearly distinguishable, has a single-layered columnar epithelium under which, in the cardiac and fundic portion, gastric glands, comprised of all similar cells, are present. The pyloric region is characterized by four caeca, to the base of which the ductus pancreaticus and the ductus hepaticus discharge.
The pancreas is composed of small masses spread along the upper intestine; in the adult, pancreatic infiltrations can be seen in the liver.
The intestine is short (relative length 0.5–0.6). The intestine epithelium consists of columnar cells intercalated with mucus-secreting cells. A funnel-like valve marks the passage to the intestine terminal region, characterized by a mucosa of cells with an abundance of vacuoles full of eosinophilic granules.     

Effect of D-galactosamine on nucleotides in the rat heart. Effects of cytidine and uridine administration

The treatment of rats by galactosamine (2 mmol/kg i.p.), which dramatically alters the metabolism of pyrimidine nucleotides in the liver, has been used to investigate the dynamics of pyrimidine nucleotides in the rat heart. Six hours after administration of the drug, the UTP and UDPG myocardial contents were decreased by respectively 40 and 52% while the sum of uracil nucleotides was increased by 66% and that of cytosine nucleotides by 15%. When administered 5 h after galactosamine treatment, cytidine (750 nmol/rat i.v.) induced a further increase in cytosine nucleotides (46% above control value 1 h later) without however effect on uracil nucleotides. On the other hand, the administration of uridine (250 nmol/rat, i.v. 5 h after galactosamine), while restoring UTP, UDPG and the pool of uracil nucleotides, provoked a decrease in cytosine nucleotide level (-17%). In the absence of galactosamine treatment, the administration of uridine and cytidine did not induce changes in nucleotide levels despite a rise in blood cytidine concentration. All these observations support the hypothesis that: 1. the pathway for cytosine nucleotide synthesis predominant in the heart is that utilizing preformed exogenous cytidine and 2. this pathway is mainly controlled by the intracellular concentration of UTP rather than that of CTP.