How females of the rotifer Asplanchna brightwelli swim in darkness and light: an automated tracking study

This work explores the effect of darkness on the swimming behaviour of females of the rotifer Asplanchna brightwelli. Females were filmed in flat dishes alternately in white light (WL, 5000 µW cm^–2) and in infra-red light (IR, 155 µW cm^–2), each female for a total of eight successive periods of fifteen minutes per period. An automated tracking system was used to describe the swimming path of each female: twenty five x and y coordinates of the center of gravity of the animal per second, in a discrete space of 512 × 512 pixels. Indices characterizing the swimming performances of the females were then calculated: linear speed, angular speed and other angular parameters of the tracks. A Principal Component Analysis of swimming characteristics discriminated between WL tracks and IR tracks. Females swam slower and turned more in darkness than in light. These results show that beside a positive phototactic response, there is a photokinesis which increases the dispersion of animals in the light.     

Interaction of HIV-1 with susceptible lymphoblastoid cells. 1H NMR studies.

Different strains of HIV susceptible lymphoblastoid cells have been infected by HIV-1 and examined by means of 1H NMR spectroscopy at different times after infection, taking advantage of the presence of high resolution lipid signals from the plasma membrane of tumor cells. A transient decrease in intensity of fatty acid signals, originated by changes in membrane structure, has been observed early after viral infection. Marked alterations in membrane-dependent steps of phospholipid synthesis can also be inferred by the observed transient depression in peaks from choline-based metabolites. Spectral modifications deriving from changes in lipid metabolism are also produced both in infected cells a few days after infection and in permanently infected cells. 1H NMR can, therefore, monitor structural and metabolic effects induced by HIV infection.     

Role of percutaneous pelvic node aspiration cytology in the management of bladder carcinoma

Six of the 23 patients with bladder carcinoma who underwent percutaneous pelvic node aspiration biopsy cytology for staging purposes showed positive findings from nodal chains. Pelvic lymphadenectomy revealed no false-positive or false-negative cytologic results. The fine needle aspiration of opacified pelvic nodes under fluoroscopic control is of great diagnostic value, with a high accuracy in detecting nodal extension of bladder carcinoma and providing a rational basis for proper therapy. Positive aspiration results may be accepted as a basis for therapeutic decisions. Since the metastatic involvement of multiple nodes makes any therapeutic treatment as well as cystectomy completely useless, positive aspirations from more than two nodes may spare patients an unnecessary radical surgery.     

Th1-Induced CD106 Expression Mediates Leukocytes Adhesion on Synovial Fibroblasts from Juvenile Idiopathic Arthritis Patients

This study tested the hypothesis that subsets of human T helper cells can orchestrate leukocyte adhesion to synovial fibroblasts (SFbs), thus regulating the retention of leukocytes in the joints of juvenile idiopathic arthritis (JIA) patients. Several cell types, such as monocytes/macrophages, granulocytes, T and B lymphocytes, SFbs and osteoclasts participate in joint tissue damage JIA. Among T cells, an enrichment of classic and non-classic Th1 subsets, has been found in JIA synovial fluid (SF), compared to peripheral blood (PB). Moreover, it has been shown that IL-12 in the SF of inflamed joints mediates the shift of Th17 lymphocytes towards the non-classic Th1 subset. Culture supernatants of Th17, classic and non-classic Th1 clones, have been tested for their ability to stimulate proliferation, and to induce expression of adhesion molecules on SFbs, obtained from healthy donors. Culture supernatants of both classic and non-classic Th1, but not of Th17, clones, were able to induce CD106 (VCAM-1) up-regulation on SFbs. This effect, mediated by tumor necrosis factor (TNF)-α, was crucial for the adhesion of circulating leukocytes on SFbs. Finally, we found that SFbs derived from SF of JIA patients expressed higher levels of CD106 than those from healthy donors, resembling the phenotype of SFbs activated in vitro with Th1-clones supernatants. On the basis of these findings, we conclude that classic and non-classic Th1 cells induce CD106 expression on SFbs through TNF-α, an effect that could play a role in leukocytes retention in inflamed joints.     

Random acrocentric bivalent associations in human pachytene spermatocytes. Molecular implications in the occurrence of Robertsonian translocations

Acrocentric bivalent associations were studied in 232 human male germ cells at pachytene in order to understand better the preferential involvement of chromosomes 13, 14, and 21 in Robertsonian translocations. The tendency of each acrocentric bivalent to associate with another was not correlated with NOR activity, as measured by silver staining. Good agreement was noticed between their ability to associate and the amount of satellite DNA in human acrocentric chromosomes. The distribution of two-by-two acrocentric bivalent associations was random. In order to reconcile this result with the nonrandom distribution of Robertsonian translocations, a molecular hypothesis is proposed. The model is based on homology of recombinational sites, interspersed at regular interval in satellite DNA, which could increase the probability of accidental unequal crossing-over between two specific acrocentric chromosomes.     

An experimental system for the automatic tracking and analysis of rotifer swimming behaviour

An automatic tracking system for rotifer swimming movements is described. The x and y coordinates of the Center of gravity of the animal are stored in the computer memory every twelfth of a second. Computer programs were developed to analyze the data and to calculate the average and the standard deviation for the following parameters per unit of time: distance traveled, turning angles toward the right and toward the left, distance from the point of departure as the crow flies. Histograms are traced by the computer showing the distribution of these values, as well as their evolution with time. This experimental system is dependable. The first values which we obtained for the swimming speed of rotifers correspond well with those which are given in the literature. The other parameters had not been measured until now.     

Pachytene analysis in a 17;21 reciprocal translocation carrier: role of the acrocentric chromosomes in male sterility

Summary Pachytene analysis was undertaken in an infertile male, heterozygous for a 17;21 reciprocal translocation. The quadrivalent was identified by its configuration and chromomere pattern. A non-random association was found between the quadrivalent and the sex vesicle in 77% of the pachytene nuclei analysed. In 13.1% of the cells the contact with the sex vesicle was established by the terminal chromomere of the two chromosomes 21; in 63.9% of the cells, the entire region of the breakpoints was completely hidden by the sex vesicle. In some nuclei asynapsis was found in the region of the breakpoints. The nature of the contact between the quadrivalent and the sex vesicle is discussed in this paper. It is proposed that the acrocentric chromosome favours the contact between the quadrivalent and the sex vesicle, and increases the risk of sterility in male carriers of Robertsonian translocations and of reciprocal translocations involving one acrocentric chromosome.     

Inhibition of the Na+/Ca2+ exchange in cardiac sarcolemmal vesicles by amiloride

The pyrazine diuretic amiloride inhibits the Na+/Ca2+ exchange activity of cardiac sarcolemmal vesicles in a concentration-dependent way. A good relationship between the uptake of amiloride by the vesicles and the inhibition of the exchanger has been found. Kinetic analyses indicate that the inhibition of Na+/Ca2+ exchange activity by amiloride is non-competitively removed by Ca2+ and competitively overcome by an outwardly directed Na+ gradient.