The planktonic rotifers of the estuarine lagunar complex of Suape (Pernambuco,Brazil)

We studied spatial and temporal distribution, abundance, diversity, equitability and species associations of the rotifers of the estuarine area of Suape (Pernambuco-Brazil), based on plankton samples collected according to the tidal regime at 11 fixed stations in Suape Bay and the estuaries of Massangana, Tatuoca and Ipojuca Rivers, during February (dry season) and July (rainy season) of 1978. Concurrent hydrological and climatological data were taken. Eight species groups were established. In general, rotifers dominated in the Ipojuca River estuary and stations subject to its influence. Greatest community similarities were observed among nearby stations, during the same tide and season. Hydrological factors influenced the occurrence and distribution of some species, and a close correlation between phytoplankton and rotifers was observed. Pollution in Ipojuca River contributed to diversity.     

Purification and characterization of a pore-forming protein from the marine sponge Tethya lyncurium.

A pore-forming protein was detected and purified for the first time from a marine sponge (Tethya lyncurium). The purified protein has a polypeptide molecular mass of 21 kDa and a pI of 6.4. Tethya pore-forming protein (also called Tethya hemolysin) rapidly lysed erythrocytes from a variety of organisms. After binding to target membranes, the hemolysin resisted elution with EDTA, salt or solutions of low ionic strength and hence resembled an integral membrane protein. Erythrocytes could be protected from hemolysis induced by Tethya hemolysin by addition of 30 mM dextran 4 (4-6 kDa; equivalent hydrodynamic diffusion radius, 1.75-2.3 nm) to the extracellular medium, but not by addition of uncharged molecules of smaller size [sucrose, raffinose and poly(ethylene glycol) 1550; equivalent hydrodynamic diffusion radii, 0.46, 0.57 and 1.2 nm, respectively]. This result indicates that hemolysin is able to form stable transmembrane pores with an effective diameter of about 2-3 nm. Treatment of osmotically protected erythrocytes with Tethya hemolysin caused a rapid efflux of intracellular K+ and ATP, and a rapid influx of extracellularly added Ca2+ and sucrose. In negative-staining electron microscopy, target erythrocyte membranes exposed to purified Tethya hemolysin displayed ultrastructural lesions but without visible pores.     

Microcarrier culture of bowes melanoma cells in serum-free medium with Human plasma fraction IV-4+ V

Bowes melanoma cells were cultivated successfully in a serum-free medium which was constructed by the concept of maximum retention of proteins from fractionated human plasma having growth stimulatory activities. The cells could be cultivated in the serum-free medium without any adaptation period. The major serum-free component of the medium was the fraction IV-4 + V of the Cohn fractionation process of human plasma. Approximately six times increase of tissue-type plasminogen activator (t-PA) activity as compared with that in serum-free medium even though the cell growth was much slower. In addition, the growth stimulatory activities of thrombin and fibronectin were investigated during the cultivation of Bowes melanoma cells in this serum-free medium. These proteins contributed significantly to the enhanced growth of cells by reducing doubling time to 25 and 35 h as compared with 55 h in the serum-free medium without them. Especially, fibronectin supported cells to propagate near to the maximum cell density achieved in the medium with 10% FBS.     

The catalytic mechanism of cytochrome P-450. Spin-trapping evidence for one-electron substrate oxidation

Cytochrome P-450 is destroyed during catalytic oxidation of several 4-substituted 3,5-bis(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine substrates. A qualitative correlation has been found between the ability to destroy cytochrome P-450 and the stability of the 4-substituent as a radical. Destruction of the enzyme by the 4-ethyl (DDEP), 4-propyl, and 4-isobutyl analogues is due to transfer of the 4-alkyl group from the substrate to a nitrogen of the prosthetic heme, a process which gives rise to isolable N-alkylprotoporphyrin IX derivatives. Little enzyme destruction is observed when the 4-alkyl group is of low radical stability (methyl, phenyl) and good destruction, but no isolable heme adducts when the 4-substituent is of very high radical stability (isopropyl, benzyl). Spin-trapping studies have established that the 4-ethyl group in DDEP is lost as a radical as a result of oxidation by cytochrome P-450. Of three commonly used spin traps, only alpha-(4-pyridyl-1-oxide) N-tert-butylnitrone was found suitable for such studies. The other spin traps, 5,5-dimethyl-1-pyrroline-N-oxide and alpha-phenyl N-tert-butylnitrone, were found to be ineffective, the latter because it strongly inhibits cytochrome P-450. Hydrogen peroxide formed in situ can support a part of the cytochrome P-450-catalyzed ethyl radical formation and DDEP-dependent self-inactivation. The results provide persuasive evidence that oxidation of the nitrogen in DDEP by cytochrome P-450 proceeds in one-electron steps. Cytochrome P-450 may thus function, at least with certain substrates, as a one-electron oxidant.     

The effect of silicon on the manganese nutrition of soybeans (Glycine max (L.) Merrill)

Summary Silicon during the early vegetative stage did not affect the oven dry weight of any of the various tissues of the soybean plant. Silicon did, however, decrease the Mn concentration in the youngest fully mature leaf at intermediate levels of Mn. This effect did not occur at the lowest or highest Mn levels. Deficiency and toxicity symptoms were moderated to a slight degree by Si except at the highest level of Mn.     

Orientation of anosmatic pigeons

Summary Test releases performed at five symmetrically arranged sites around the loft, at a distance of 78–99 km from it, showed that 1) anosmatic birds transported without alteration of the earth's magnetic field were completely random-oriented, 2) anosmatic birds transported in a container inside which the intensity of the magnetic field was strongly reduced were unable to orientate homewards and mostly departed according to a preferred compass direction, 3) control birds, which could smell, and were transported without alteration of the magnetic field, were homeward oriented and performed better in homing than both experimental groups. The conclusion is that anosmatic birds are unable to detect home direction at unfamiliar sites and that magnetic stimuli perceived during the outward journey are unable to substitute olfactory cues.Abbreviation PCD preferred compass direction Supported by a grant from the Consiglio Nazionale delle Ricerche     

The effect of diphenols upon the autoxiation of oxyhemoglobin and oxymyoglobin.

P-Hydroquinone and catechol catalytically promote the oxidation of oxyhemoglobin and Oxymyoglobin to the ferriform. Kinetic data for oxyhemoglobin oxidation indicates a first-order dependence upon the hemeprotein concentration and half-order dependence upon diphenol; however at high catalyst concentration, saturation is observed with similar V values for both diphenols despite the difference in reactivity.It is proposed that initially formed quinone oxidizes the hemeprotein with oxygen release; in turn, the semiquinone oxidizes a second molecule of hemeprotein and regenerates the quinone, with the bound oxygen acquiring two electrons. Except for the more reactive oxymyoglobin, the reduced form of the catalyst must be present to oppose semiquinone disappearance by dismutation.Since the expected release of O₂ for water formation is observed, the system may be considered a model for terminal oxidase, the couple $\text{Q}\text{S}$ replacing a $\text{Fe}{}^{\mathrm{2+}}\text{Fe}{}^{\mathrm{2+}}$ or a $\text{Cu}{}^{\mathrm{+}}\text{Cu}{}^{\mathrm{2+}}$ system.It is tentatively inferred that oxyhemoglobin has the structure HbFe²⁺---O₂ and that the rate of the catalyzed oxidation is limited by the rate of generation of the true reacting form, the superoxide ferri structure, HbFe³⁺---O₂^?.     

MicroRNA 320a and Membrane Antigens as Tools to Evaluate the Pathophysiology of Platelets Stored in Blood Banks

Our research group, through the analysis of miRNomes in platelet concentrates (PCs) stored in blood banks, identified and validated the miR-127 and miR-320a miRNAs as biomarkers of platelet storage lesions (PSLs) in PCs. In order to validate the miRNAs 127 and 320a methodologically, as PSL biomarkers in a large number of PC bags, we also evaluated important immunological markers involved in the platelet activation/aggregation process—the CD62P receptor (P-selectin), the surface glycoproteins (GP) IIb/IIIa, and the purinergic P2Y12 receptor—via flow cytometry. The miRNAs miR-127 and miR-320a were quantified by real-time quantitative PCR (RT-qPCR). To carry out this study, 500 collection tubes were used at the upper edge of the PC bags containing platelets. Each tube was divided into seven equal parts (totaling 3500 samples) for platelet analysis from 7 different storage days, where the 1st day represents the high-quality control, and the 7th day corresponds to the low-quality control of the platelets. After analyzing all parameters during storage days, it was concluded that the relative quantification of miR-320a below 0.50 and the CD62P receptor below 27.92% are reliable indicators of the absence of storage lesions in blood banks. We believe that the values found in the expression of the CD62P receptor legitimize the use of the miR-320a and miR-127 miRNAs to build a kit capable of accurately measuring whether the stored platelets are suitable for transfusion.