The chimeric cytokine Hyper-IL-6 enhances the efficiency of lentiviral gene transfer in hepatocytes both in vitro and in vivo

Lentiviral vectors have been used for gene transfer into the liver but their ability to efficiently transduce quiescent hepatocytes remains controversial. Lentivirus-mediated gene transfer is more efficient in cycling cells. We determine the effect of H-IL6 in the lentiviral transduction. The lentiviral vector was used to transduce HepG2 cells and mice liver cells, previously treated with H-IL6. The highest transduction level was observed in HepG2 cells treated with 30 ng/mL H-IL6 and in the mice that received 4 μg H-IL6. Our results suggest that H-IL6 is an inducer of lentiviral gene transfer into the liver cells without any toxicity.     

Cytoplasmic incompatibilities in the mosquito Culex pipiens: How to explain a cytotype polymorphism?*

Although cytoplasmic incompatibilities have been used as a means of eradicating the mosquito Culex pipiens, the population dynamics of these sterilities in relation to the coexistence of multiple incompatible cytotypes in a single area has not been investigated, except in the case of two unidirectionally incompatible cytotypes. An analytical model of the evolution of n cytotypes in an infinite panmictic population has been developed in order to investigate polymorphic equilibrium. A necessary criterion for the stability of such an equilibrium is established; it is shown that a stable polymorphism cannot exist between incompatible cytotypes. This result is discussed in the light of population dynamics and genetics of Culex pipiens, and of our present knowledge on incompatibilities. The consequences of a geographic structuring and of homogamy are considered. A careful reconsideration of previous experimental results disclosed probable nuclear effects and a serious experimental weakness: with the common procedure of backcrossing hybrid females to males of constant genotype it is not possible to rule out probable nuclear effects with paternal expression. It is concluded that incompatibilities in Culex pipiens may have a nuclear-cytoplasmic determinism.     

Vibration attraction response is a plastic trait in blind Mexican tetra (Astyanax mexicanus), variable within subpopulations inhabiting the same cave

Animals evolve their sensory systems and foraging behaviours to adapt and colonize new and challenging habitats such as the dark cave environment. Vibration attraction behaviour (VAB) gives fish the ability to locate the source of a water disturbance in the darkness. VAB evolved in the blind Mexican cave tetra, Astyanax mexicanus. VAB is triggered in cavefish by vibration stimuli peaking at 35 Hz, which is within the main spectrum of water fluctuations produced by many prey crustaceans and insects. VAB has a genetic component and is correlated to an increased number of head mechanosensory neuromasts in the eye orbital region when compared to surface fish. Previous competitive prey capture assays have supported the advantage of VAB for foraging in the dark. Despite its putative adaptive function, VAB has been described as absent in some Astyanax cave populations (Tinaja and Molino) but present in others (Pachón, Piedras, Toro and Sabinos). Here we have tested the occurrence of VAB in the field and in multiple cave populations using a vibrating device in natural pools. Our results confirmed the presence of VAB in caves such as Pachón, Toro and Sabinos but showed that VAB is also present in the Tinaja and Molino cave populations, previously reported as VAB-negative in laboratory experiments. Thus, VAB is available throughout the range of hypogean A. mexicanus. However, and most notably, within a given cave the levels of VAB were highly variable among different pools. Fish at one pool may express no VAB, while fish at another nearby pool of the same cave may actively show VAB. While a variety of environmental conditions may foster this diversity, we found that individuals inhabiting pools with a high abundance of organic matter have reduced expression of VAB. In contrast, in pools with little organic debris where fish probably depend more on hunting than on scavenging, VAB is enhanced. Our results suggest that expression of VAB is a plastic trait whose variability can depend on local conditions. Such plasticity may be required within and among caves where high environmental variability between pools results in a diverse availability of food.     

The porcine trophoblastic interferon-gamma, secreted by a polarized epithelium, has specific structural and biochemical properties.

At the time of implantation in the maternal uterus, the trophectoderm of the pig blastocyst is the source of a massive secretion of interferon-gamma (IFN-gamma), together with lesser amounts of IFN-delta, a unique species of type I IFN. This trophoblastic IFN-gamma (TrIFN-gamma) is an unprecedented example of IFN-gamma being produced spontaneously by an epithelium. We therefore studied some of its structural and biochemical properties, by comparison with pig IFN-gamma from other sources, either natural LeIFN-gamma (from adult leucocytes), or recombinant. Biologically active TrIFN-gamma is a dimeric molecule, of which monomers are mainly composed of a truncated polypeptide chain with two glycotypes, unlike LeIFN-gamma which is formed of at least two polypeptide chains and four glycotypes. TrIFN-gamma collected in the uterus lumen was enzymatically deglycosylated and analysed by mass spectrometry (MALDI-TOF). The data revealed that the more abundant polypeptide has a mass of 14.74 kDa, corresponding to a C-terminal cleavage of 17 residues from the expected 143-residue long mature sequence. A minor polypeptide, with a mass of 12.63 kDa, corresponds to a C-terminal truncation of 36 amino acids. MALDI-TOF analysis of tryptic peptides from the glycosylated molecule(s) identifies a single branched carbohydrate motif, with six N-acetylgalactosamines, and no sialic acid. The only glycan microheterogeneity seems to reside in the number of l-fucose residues (one to three). The lack of the C-terminal cluster of basic residues, and the presence of nonsialylated glycans, result in a very low net charge of TrIFN-gamma molecule. However, the 17-residue truncation does not affect the antiproliferative activity of TrIFN-gamma on different cells, among which is a porcine uterine epithelial cell line. It is suggested that these specific properties might confer on TrIFN-gamma a particular ability to invade the uterine mucosa and exert biological functions beyond the endometrial epithelium.