Thermal Marangoni bubbles.

When air reaches the surface of a pool (or bath) of pure liquid, it does not form long-lasting bubbles, as opposed to when the bath contains surfactants. Here we describe what happens when the pool is pure (consisting of oil), yet hot. The bubbles dwelling at the surface can then live for minutes or even longer, which we interpret as a consequence of the gradients of temperature generated in this experiment.

When Elasticity Affects Drop Coalescence.

The breakup and coalescence of drops are elementary topological transitions in interfacial flows. The breakup of a drop changes dramatically when polymers are added to the fluid. With the strong elongation of the polymers during the process, long threads connecting the two droplets appear prior to their eventual pinch-off.

Thermophobic Leidenfrost.

We report that a volatile liquid deposited on a hot substrate with a gradient of temperature does not only levitate (Leidenfrost effect), but also spontaneously accelerates to the cold. This thermophobic effect is also observed with sublimating solids, and we attribute it to the ability of temperature differences to tilt (slightly) the base of the "object", which induces a horizontal component to the levitating force. This scenario is tested by varying the drop size (with which the acceleration increases) and the substrate temperature (with which the acceleration decreases), showing that the effect can be used to control, guide and possibly trap the elusive Leidenfrost drops.

Self-excitation of Leidenfrost drops and consequences on their stability.

Volatile liquids (water, alcohol, etc.) poured on hot solids levitate above a layer of vapor. Unexpectedly, these so-called Leidenfrost drops often suddenly start to oscillate with star shapes, a phenomenon first reported about 140 y ago.

Buoyancy-driven convection of droplets on hot nonwetting surfaces.

The global linear stability of a water drop on hot nonwetting surfaces is studied. The droplet is assumed to have a static shape and the surface tension gradient is neglected. First, the nonlinear steady Boussinesq equation is solved to obtain the axisymmetric toroidal base flow.

Aerotaxis in the closest relatives of animals.

As the closest unicellular relatives of animals, choanoflagellates serve as useful model organisms for understanding the evolution of animal multicellularity. An important factor in animal evolution was the increasing ocean oxygen levels in the Precambrian, which are thought to have influenced the emergence of complex multicellular life. As a first step in addressing these conditions, we study here the response of the colony-forming choanoflagellate to oxygen gradients.

[The bovine immunodeficiency virus: 1990-1992 update].

Substantial progress has been shown on the bovine immunodeficiency-like virus (BIV) in 1990-1991 and up to mid-1992. The genomic sequences of BIV were analysed in detail and several subgenomic RNAs were identified. Nucleic acid molecular probes, PCR (polymerase chain reaction) amplification and a novel Western blotting procedure have been of great assistance for the experimental diagnosis of BIV.

[Bovine immunodeficiency virus: short review].

A bovine visna-like virus was isolated by Van Der Maaten et al (1972) but it did not draw attention since, at that time, most efforts were directed towards research on bovine leukemia virus. However, new interest was shown on the bovine visna-like virus after the isolation of the human immunodeficiency virus (HIV), because of the urgent need for developing animal models for the acquired immunodeficiency syndrome (AIDS). The purpose of this paper is to describe the different stages of the identification of the bovine virus and to up-date knowledge about it.

Replication of the bovine immunodeficiency-like virus in diploid and aneuploid cells: permanent, latent and virus-productive infections in vitro.

Bovine immunodeficiency-like virus (BIV) is an infectious and leukotropic retrovirus, the sole lentivirus candidate which has been isolated from cattle. Although BIV has recently been shown to be related to the human immunodeficiency virus, there is very limited information on the replication and the pathogenesis of BIV. It is reported here that BIV can permanently infect diploid and aneuploid cells from four different species: bovine, canine, ferret and ovine.

A comparison of the bovine leukemia and bovine syncytial virus status in utero-tubal cells recovered from fluids used to flush the uterus and oviducts of BLV-infected, superovulated cattle.

Twenty-four cell lines were established from uterine-oviductal flush fluid (UOFF) cells from 20 bovine leukosis virus (BLV)-infected embryo-donor cows and 4 BLV-free control cows harvested by the Ficoll-gradient technique. Similar epithelial-like and fibroblast-like cells were observed in the primary cultures of UOFF from both groups. BLV-antigens were not detected with direct immunofluorescence test in any of the cell-lines from the 20 positive BLV-cows but a positive reaction was observed with the competitive radioimmunoassay in one cell line only.

Analogy between lymphotropic human retroviruses and large animal retroviruses.

The family Retroviridae comprises some fifty viruses in three subfamilies: Oncoviridae, Lentiviridae and Spumaviridae. A better understanding of retroviral pathobiology has resulted from the rapid developments in knowledge of the molecular biology of normal and cancerous cells as well as retroviruses. Genomic relatedness was found between two human T cell leukemia viruses and bovine leukemia virus, similarly, some relatedness appears possible between human AIDS (acquired immunodeficiency syndrome) virus and lentiviruses of large animals.

The persistent infection of a canine thymus cell line by equine infectious anaemia virus and preliminary data on the production of viral antigens.

Equine infectious anaemia virus (EIAV) was adapted to the Cf2Th cell line, a heterologous malignant line from canine thymus. A persistent infection was monitored for 100 serial passages by demonstrating the presence of virus and viral antigens at each 10th passage by electron-microscopy, immunodiffusion and immunofluorescence. Chromosome analysis of EIAV-infected cells indicated they had a karyotype resembling the control cells of similar passage history.

Analogie entre les rétrovirus humains lymphotropes et les rétrovirus des grands animaux.

The family Retroviridae comprises some fifty viruses in three subfamilies: Oncoviridae, Lentiviridae and Spumaviridae. A better understanding of retroviral pathobiology has resulted from the rapid developments in knowledge of the molecular biology of normal and cancerous cells as well as retroviruses. Genomic relatedness was found between two human T cell leukemia viruses and bovine leukemia virus; similarly, some relatedness appears possible between human AIDS (acquired immunodeficiency syndrome) virus and lentiviruses of large animals.

Embryo transfer in relation to bovine leukemia virus control and eradication.

Two hundred and seven, zona pellucida-intact bovine embryos were collected from bovine leukemia virus-infected donors, washed, and transferred to uninfected recipients: 111 of these embryos were sired by bovine leukemia virus-infected bulls. Fifty live calves were obtained from the 57 pregnancies resulting from the transfers. None of the recipients or calves developed antibodies to bovine leukemia virus.

[Chromosomes and carcinogenesis. Study on the evolution of an epithelial cell line of porcine origin].

The PFT cell line was established in 1969 from diploid cells of the inner lining of a uterine tube of a 2 year-old sow and has been continuously subcultured more than 500 times over a decade. Three chromosomal rearrangements have occurred during this time. The first translocation was shown at the 100th passage with the concomitant and spontaneous release of an endogeneous type C virus.

Isolation of bovine syncytial virus from lymphocytes recovered from fluids used to flush uterus and oviducts of superovulated cattle.

A Ficoll-gradient method was applied to isolate lymphocytes from fluids used to flush the uterus and oviducts of superovulated cows. Bovine syncytial virus antigens were demonstrated in 15 of 19 cows by cocultivation of lymphocytes with fetal lamb spleen cells and examining them with direct immunofluorescence. Viral serum antibodies were found in the same 15 of 19 cows as above by the modified direct complement-fixation test.

Ultrastructural comparison of Oncovirinae (type C), Spumavirinae, and Lentivirinae: three subfamilies of Retroviridae found in farm animals.

The successive steps of maturation of seven retroviruses from five species of farm animals and one retrovirus from a mouse were compared in cell cultures. The viruses included three type C oncoviruses, one spumavirus, and three lentiviruses. Although members of the 3 subfamilies shared some gross morphologic features such as budding on plasma membranes, core, and surface projections, differences were noted in the ultrastructural detail of these features.

Enzyme linked immunosorbent assay (ELISA) for the detection of antibodies to porcine cytomegalovirus.

The ELISA and indirect immunofluorescence test were compared on 56 porcine sera which were tested for antibodies to porcine cytomegalovirus. Viral antigens were prepared in cells of a pig fallopian tube line. The ELISA was found to be a sensitive reproducible and practical test to measure specific antibodies to this infection.

Attempts to isolate bovine leukemia and bovine syncytial viruses from blood, uterine flush fluid, unfertilized ova and embryos from infected donor cattle.

Blood leucocytes, sediments of uterine flush fluid (UFF), eggs and embryos from 25 BLV-positive donor cows were tested for bovine leukemia (BLV) and bovine syncytial (BSV) viruses by cocultivation with fetal lamb spleen cells and by applying syncytium induction and immunofluorescence tests. BLV was diagnosed in 11/15 (73.3%) leucocyte and 4/25 (16.

Nontumoral, benign ad malignant stages of transformation of a diploid pig cell line. A review.

The PFT cell line originated from diploid endometrial cells and was subcultured more than 500 times. Nontumoral, benign and malignant transformation appeared at different stages. Four populations (F1, F2, F3 and F4) of cells were demonstrated sequentially by chromosomes analysis.

Concanavalin A agglutination assays in the multistage transformation of a pig cell line.

Cells of a pig Fallopian tube line were agglutinated by concanavalin A (Con A). Similar ConA agglutination was shown in diploid and nontumoral transformed cells with one (T1) translocation until the 112th subculture. Then a progressive increase of agglutination was shown until the 149th subculture and the rate of agglutination remained constant thereafter.

Multisequential transformation of a pig cell line (PFT): correlations between tumorigenicity and chromosome and ultrastructural markers.

Cells from representative subcultures of a continuous cell line of pig uterine tube (PFT) and carrying none, one, or two chromosome markers were inoculated in athymic nude mice (RCN) to determine the occurrence of the malignant transformation in this line. No tumors developed in mice after implantation of cells from either the 16th and 65th subcultures (no chromosome markers) or the 106th subculture (one chromosome marker, anchorage-dependent). Three adenomas (11.

Production of tumors in hamsters by cells of a pig uterine tube line.

Tumorigenicity was investigated in a pig established cell line continuously subcultured more than 400 times. Tumors were not found in hamsters' cheek pouches inoculated with cells from the first 200 subcultures. Fibroma developed in five out of 13 animals (9/26 pouches) inoculated with cells of the 313th and 314th subcultures.

Evidence of a mixed population from uterine tube epithelium in a continuous line of pig cells.

The pig uterine tube (PFT) cell line is composed of a mixed population which is undifferentiated. However, specific markers indicating the original tissue of the uterine tube were shown if cells differentiated into epithelial cells forming spheroids in the 254th subculture. Ciliated and secretory cells, and cells with a basal lamina and interstitial collagen were observed in the spheroids.