Patterns of Sleeping Site and Sleeping Tree Selection by Black-and-Gold Howler Monkeys (Alouatta caraya) in Northern Argentina

International Journal of Primatology - The selection of sleeping sites and sleeping trees in nonhuman primates is related to social and ecological factors. We investigate the role of body...     

Ubiquinol prevents alpha-tocopherol consumption during liposome peroxidation

In this study we investigated whether alpha-tocopherol can be spared by ubiquinol-3 during autoxidation of multilamellar liposome. A lipophilic azocompound, 2,2'-azobis-(2,4-dimethyl-valeronitrile), was chosen to initiate liposome autoxidation. The effect of either alpha-tocopherol, ubiquinol-3, or a mixture of them was compared. Rates of conjugated diene formation and concomitant disappearance of the two antioxidants was measured. Since the inhibition rate constant for the scavenging of peroxyl radical for alpha-tocopherol was higher than that for quinol-3, it was concluded that alpha-tocopherol is regenerated by ubiquinol-3.     

Analysis of Immune Response Markers in Jorge Lobo's Disease Lesions Suggests the Occurrence of Mixed T Helper Responses with the Dominance of Regulatory T Cell Activity

Jorge Lobo’s disease (JLD) is a chronic infection that affects the skin and subcutaneous tissues. Its etiologic agent is the fungus Lacazia loboi. Lesions are classified as localized, multifocal, or disseminated, depending on their location. Early diagnosis and the surgical removal of lesions are the best therapeutic options currently available for JLD. The few studies that evaluate the immunological response of JLD patients show a predominance of Th2 response, as well as a high frequency of TGF-β and IL-10 positive cells in the lesions; however, the overall immunological status of the lesions in terms of their T cell phenotype has yet to be determined. Therefore, the objective of this study was to evaluate the pattern of Th1, Th2, Th17 and regulatory T cell (Treg) markers mRNA in JLD patients by means of real-time PCR. Biopsies of JLD lesions (N = 102) were classified according to their clinical and histopathological features and then analyzed using real-time PCR in order to determine the expression levels of TGF-β1, FoxP3, CTLA4, IKZF2, IL-10, T-bet, IFN-γ, GATA3, IL-4, IL-5, IL-13, IL-33, RORC, IL-17A, IL-17F, and IL-22 and to compare these levels to those of healthy control skin (N = 12). The results showed an increased expression of FoxP3, CTLA4, TGF-β1, IL-10, T-bet, IL-17F, and IL-17A in lesions, while GATA3 and IL-4 levels were found to be lower in diseased skin than in the control group. When the clinical forms were compared, TGF-β1 was found to be highly expressed in patients with a single localized lesion while IL-5 and IL-17A levels were higher in patients with multiple/disseminated lesions. These results demonstrate the occurrence of mixed T helper responses and suggest the dominance of regulatory T cell activity, which could inhibit Th-dependent protective responses to intracellular fungi such as L. loboi. Therefore, Tregs may play a key role in JLD pathogenesis.     

A note on the feeding ofAmphichaeta leydigii (Oligochaeta,Naididae) in lacustrine sandy shores

The analysis of gut contents ofAmphichaeta leydigii, found for the first time in Italy in sandy shores of Lake Vico (Central Italy), proved grazing of the species on diatoms (Centrales and Pennales). Detritus and organic particles, abundant in the substratum, were observed only in small amounts.     

Mechanism of interaction of the cyanine dye DiS−C3-(5) with renal brush-border vesicles

Summary The equilibrium binding mechanism and kinetics of binding of diS–C₃-(5) (3,3-dipropylthiodicarbocyanine iodide) to rabbit renal brush-border membrane vesicles (BBMV) were examined using steady-state and time-resolved fluorescence, and fluorescence stopped-flow methods. In aqueous solution, diS–C₃-(5) exists as a monomer at concentrations <5 m with fluorescence emission peak at 670 nm (excitation 622 nm), anisotropyr=0.102, and lifetime =1.2 nsec (23°C). Upon addition of increasing BBMV (voltage clamped to 0 mV using K⁺/valinomycin), the 670 nm emission peak decreases, corresponding to formation of a nonfluorescent membrane dimer, and subsequently a new emission peak at 695 nm increases, corresponding to membrane monomer. Dynamic depolarization studies show that aqueous diS–C₃-(5) rotation is unhindered with a rotational rateR=0.57 nsec^–1 while membrane monomer is hindered with steady-state anisotropyr=0.190, lifetime =2.1 nsec,R=0.58 nsec^–1 and limiting anisotropyr =0.11. Based on equilibrium fluorescence titrations, the membrane monomer-dimer (M-D) dissociation constant,K _d=[M]²/[D][BBMV], is 0.0013, where BBMV is expressed as membrane phospholipid concentration. Three distinct kinetic processes are identified by stopped-flow experiments in which BBMV are mixed with diS–C₃-(5). There is rapid binding of diS–C₃-(5) to the membrane to form bound monomer with a 6-msec exponential time constant. The membrane monomer at the membrane outer surface then aggregates to form bound dimer at the outer surface with a concentration independent time constant of 30 msec. The overall dimerization reaction probably consists of a rate-limiting reorientation process (30 msec) followed by a rapid dimerization which occurs on a nanosecond time scale. Finally, there is a 0.8 to 1 sec translocation of membrane dimer between symmetric sites at the inner and outer membrane surfaces. The translocation reaction is the step which is probably sensitive to changes in transmembrane electrical potential.     

The influence of poly(ethylene glycol) 6000 on spermine-induced aggregation of liposomes.

Poly(ethylene glycol) 6000 affected the aggregation of mixed liposomes induced by spermine. It lowered the concentration of spermine causing 50% maximal aggregation, accelerated the rate and increased the extent of aggregation. The effect was inversely proportional to the density of the acidic phospholipid in the vesicles. These effects were not due either to poly(ethylene glycol) 6000-induced permanent structural modification of the liposome or increased binding of spermine to the vesicles. These findings are discussed in relation to a decreased hydration force caused by the ability of poly(ethylene glycol) 6000 to alter the water of hydration of the phospholipid polar groups in the liposome.     

Lipid Peroxidation. Definition of Experimental Conditions for Selective Study of the Propagation and Termination Phases

To find experimental conditions to selectively study the propagation phase of lipoperoxidation we studied the lipoperoxidation, catalyzed by FeCl₂, of liposomes in a buffering condition where Fe²⁺ autoxidation and oxygen active species generation does not occur. Liposomes from egg yolk phosphatidylcholine. prepared by vortex mixing, do not oxidize Fe²⁺: on the contrary they oxidize Fe²⁺ when prepared by ultrasonic irradiation. Dimyristoyl phosphatidylcholine liposomes prepared by ultrasonic irradiation do not oxidize Fe²⁺. During sonication polyunsaturated fatty acid residues autoxidize and lipid hydroperoxides (LOOH) are generated. Only when LOOH are present in the liposimes Fe²⁺ oxidizes and its rate of oxidation depends on the amount of LOOH in the assay. The reaction results in the generation of both LOOH and thiobarbituric acid reactive material (TBAR): it is inhibited by butylated hydroxytoluene and has a acidic pH optimum; it is not inhibited by catalase and OH' scavengers. The reaction studied. thus, appears to be the chain branching and propagation phase of lipoperoxidation. When we studied the dependence of Fe²⁺ oxidation, LOOH and TBAR generation on FeCl₂ concentration, we observed that at high FeCl₂ concentrations the termination phase of lipoperoxidation was prevalent. Thus. by selecting the appropriate FeCl₂ concentration the proposed experimental system allows study of either the propagation or the termination phase of lipoperoxidation.     

A PCR-based test suitable for screening for fragile X syndrome among mentally retarded males

Ever since the identification of the genetic cause of fragile X syndrome as the expansion of an unstable trinucleotide sequence, several diagnostic strategies have evolved from molecular studies. However, we still lack a simple test suitable for population screening. We have therefore developed a nonisotopic polymerase chain reaction (PCR)-based technique for the identification of fragile X full mutations among men, with easy visualization of the PCR products on silver-stained polyacrylamide gels. The technique consists of PCR amplification with primers that flank the trinucleotide repeats, with a product of 557 bp for the (CGG)₂₉ allele. Conditions were established such that full mutations failed to amplify and were thus identified with 98% sensitivity compared with Southern blot analysis. To produce an indispensable internal control we added to the reaction a third primer, internal to this fragment, allowing the multiplex amplification of a monomorphic band corresponding to a CG-rich stretch 147 bp upstream of the polymorphic region. In trials involving 41 patients and 74 controls, the PCR-based test here described showed specificity of more than 98.6%, accuracy of 99% and a sensitivity of 98%. Thus, although not suitable for medical diagnosis, it constitutes a useful tool for screening for the fragile X syndrome in populations of mentally retarded males. Received: 31 May 1995 / Revised: 4 October 1995     

Identification of P-glycoprotein at the membrane of mast cell secretory granules. An immunofluorescence and protein A-gold electron microscopical investigation

The presence of P-glycoprotein has been investigated in rat peritoneal mast cells by means of immunofluorescence and immunogold electron microscopy, using the specific monoclonal antibody JSB-1. Immunofluorescence studi es showed that the glycoprotein is primarily concentrated in mast cell granules, and little is localized at the plasma membrane. Electron microscope observations revealed a marked accumulation of colloidal gold particles at the granule-coating membranes, whereas decoration of the plasma membrane is much less intense. When mast cells are stimulated to exocytate with compound 48/80, both immunofluorescence and electron microscopy showed concentration of P-glycoprotein reactivity at the plasma membrane level. Indeed, fusion of the granule with the plasma membrane allowed transfer of immunoreactive P-glycoprotein material from the granule-coating membrane to the cell surface membrane. These findings confirmed the presence of P-glycoprotein in mast cells; it is predominantly localized in the granules and is exposed on the cell surface only after exocytosis, suggesting, therefore, a possible physiological role for P-glycoprotein in the secretion of certain mediators. This revised version was published online in November 2006 with corrections to the Cover Date.