Hepatic VLDL-TG production and MTP gene expression are decreased in ovariectomized rats: effects of exercise training

The present study was designed to investigate the effects of estrogen withdrawal and exercise training on hepatic very low density lipoprotein-triglyceride (VLDL-TG) production and on expression of genes involved in hepatic VLDL synthesis in response to lipid infusion. Female Sprague-Dawley rats underwent ovariectomy (Ovx), sham surgery (Sham), and Ovx with 17β-estradiol supplementation (OvxE2) before being subdivided into sedentary (Sed) and trained (Tr) groups for 8 weeks. Exercise training consisted of continuous running on a rodent treadmill 5 times/wk. At the end of the 8-week period, all rats in the fasted state were intravenously infused with a 20% solution of Intralipid for 3-h followed by an injection of Triton WR-1339 to block lipoprotein lipase activity. Plasma TG accumulation was subsequently measured during 90 min to estimate VLDL-TG production. An additional control group consisting of Sham-Sed rats was infused with saline (0.9% NaCl). Estrogen withdrawal resulted in higher (p<0.01) liver fat accumulation concomitantly with lower (p<0.01) VLDL-TG production and lower mRNA and protein content of hepatic microsomal triglyceride transfer protein (MTP). All of these effects in Ovx rats were corrected with estrogen supplementation. Training in Ovx rats reduced (p<0.01) liver fat accumulation and further reduced (p<0.01) hepatic VLDL-TG production along with gene expression of MTP and diacylglycerol acyltransferase-2 (DGAT-2). It is concluded that VLDL-TG synthesis and/or secretion is decreased in Ovx rats probably via MTP regulation and that this decrease may constitute one of the factors involved in hepatic fat accumulation. The training effect on reducing VLDL production was independent of the estrogenic status.     

Expression and function of aquaporins in human skin: Is aquaporin-3 just a glycerol transporter?

The aquaporins (AQPs) are a family of transmembrane proteins forming water channels. In mammals, water transport through AQPs is important in kidney and other tissues involved in water transport. Some AQPs (aquaglyceroporins) also exhibit glycerol and urea permeability. Skin is the limiting tissue of the body and within skin, the stratum corneum (SC) of the epidermis is the limiting barrier to water loss by evaporation. The aquaglyceroporin AQP3 is abundantly expressed in keratinocytes of mammalian skin epidermis. Mice lacking AQP3 have dry skin and reduced SC hydration. Interestingly, however, results suggested that impaired glycerol, rather than water transport was responsible for this phenotype. In the present work, we examined the overall expression of AQPs in cells from human skin and we reviewed data on the functional role of AQPs in skin, particularly in the epidermis. By RT-PCR on primary cell cultures, we found that up to 6 different AQPs (AQP1, 3, 5, 7, 9 and 10) may be selectively expressed in various cells from human skin. AQP1, 5 are strictly water channels. But in keratinocytes, the major cell type of the epidermis, only the aquaglyceroporins AQP3, 10 were found. To understand the role of aquaglyceroporins in skin, we examined the relevance to human skin of the conclusion, from studies on mice, that skin AQP3 is only important for glycerol transport. In particular, we find a correlation between the absence of AQP3 and intercellular edema in the epidermis in two different experimental models: eczema and hyperplastic epidermis. In conclusion, we suggest that in addition to glycerol, AQP3 may be important for water transport and hydration in human skin epidermis.     

Constitutive delivery of bovine beta-lactoglobulin to the digestive tracts of gnotobiotic mice by engineered Lactobacillus casei

The gut microbiota is critical for maturation of the immune system. Recent evidence suggests that early establishment of lactobacilli in the intestinal microbiota, during neonatal colonization or by probiotic supplementation, could prevent the development of allergic disorders. Postnatal maturation of the gut immune system with allergen-producing lactobacilli colonizing the digestive tract could then affect the development of further allergic sensitization. In this paper, we describe construction of a recombinant Lactobacillus casei strain that can constitutively deliver bovine beta-lactoglobulin (BLG), a major cow's milk allergen, to the guts of gnotobiotic mice. The blg gene was inserted into the L. casei chromosome downstream of an endogenous promoter. BLG production was improved by fusing the propeptide LEISSTCDA (LEISS) to the BLG mature moiety. This led to a 10-fold increase in LEISS-BLG production compared to the production obtained without the propeptide and also led to enhanced secretion corresponding to 5% of the total production. After inoculation into germfree C3H/HeN mice, the genetic stability of the recombinant strain and in vivo BLG production were confirmed for at least 10 weeks. BLG stimulation of spleen cells from mice monoassociated with the BLG-producing lactobacilli induced secretion of the Th1 cytokine gamma interferon and, to a lesser extent, the Th2 cytokine interleukin-5. No BLG-specific immunoglobulin G1 (IgG1), IgG2a, or IgA was detected in sera or in fecal samples. These results suggest that gut colonization with allergen-producing lactobacilli could provide a useful model for studying the modulation of allergic disorders.     

Mössbauer identification of a protonated ferryl species in catalase from Proteus mirabilis: density functional calculations on related models

The Proteus mirabilis catalase is one of the most efficient heme-containing catalase and forms a relatively stable compound II. Samples of compound II were prepared from PMC enriched in (57)Fe. For the first time, two different forms of compound II, namely low pH compound II (LpH II) (43%) and high pH compound II (HpH II) (25%), have been characterized by M?ssbauer spectroscopy at pH 8.3. The ratio LpH II/HpH II increases irreversibly with decreasing pH. The large quadrupole splitting value of LpH II (DeltaE(Q)=2.29 (2) mm/s, with delta(/Fe)=0.03 (2) mm/s), compared to that of HpH II (DeltaE(Q)=1.47 (2) mm/s, with delta(/Fe)=0.07 (2) mm/s), reflects the protonation of the ferryl group. Quadrupole splitting values of 1.46 and 2.15mm/s have been computed by DFT for optimized models of the ferryl compound II (model 1) and the protonated ferryl compound II (model 2), respectively, starting from the Fe(IV)O model initially published by Rovira and Fita [C. Rovira, I. Fita, J. Phys. Chem. B 107 (2003) 5300-5305]. Therefore, we attribute the LpH II compound to a protonated ferryl Fe(IV)-OH complex, whereas the HpH II compound corresponds to the classical ferryl Fe(IV)O complex.     

Estimating individual contributions to population growth: evolutionary fitness in ecological time

Ecological and evolutionary change is generated by variation in individual performance. Biologists have consequently long been interested in decomposing change measured at the population level into contributions from individuals, the traits they express and the alleles they carry. We present a novel method of estimating individual contributions to population growth and changes in distributions of quantitative traits and alleles. An individual's contribution to population growth is an individual's realized annual fitness. We demonstrate how the quantities we develop can be used to address a range of empirical questions, and provide an application to a detailed dataset of Soay sheep. The approach provides results that are consistent with those obtained using lifetime estimates of individual performance, yet is substantially more powerful as it allows lifetime performance to be decomposed into annual survival and fecundity contributions.     

Transfer of a chromosomal <Emphasis Type="Italic">Maverick</Emphasis> to endogenous bracovirus in a parasitoid wasp

Bracoviruses are used by parasitoid wasps to allow development of their progeny within the body of lepidopteran hosts. In parasitoid wasps, the bracovirus exists as a provirus, integrated in a wasp chromosome. Viral replication occurs in wasp ovaries and leads to formation of particles containing dsDNA circles (segments) that are injected into the host body during wasp oviposition. We identified a large DNA transposon Maverick in a parasitoid wasp bracovirus. Closely related elements are present in parasitoid wasp genomes indicating that the element in CcBV corresponds to the insertion of an endogenous wasp Maverick in CcBV provirus. The presence of the Maverick in a bracovirus genome suggests the possibility of transposon transfers from parasitoids to lepidoptera via bracoviruses.     

Possible overestimation of surface disinfection efficiency by assessment methods based on liquid sampling procedures as demonstrated by in situ quantification of spore viability

The standard test methods used to assess the efficiency of a disinfectant applied to surfaces are often based on counting the microbial survivors sampled in a liquid, but total cell removal from surfaces is seldom achieved. One might therefore wonder whether evaluations of microbial survivors in liquid-sampled cells are representative of the levels of survivors in whole populations. The present study was thus designed to determine the "damaged/undamaged" status induced by a peracetic acid disinfection for Bacillus atrophaeus spores deposited on glass coupons directly on this substrate and to compare it to the status of spores collected in liquid by a sampling procedure. The method utilized to assess the viability of both surface-associated and liquid-sampled spores included fluorescence labeling with a combination of Syto 61 and Chemchrome V6 dyes and quantifications by analyzing the images acquired by confocal laser scanning microscopy. The principal result of the study was that the viability of spores sampled in the liquid was found to be poorer than that of surface-associated spores. For example, after 2 min of peracetic acid disinfection, less than 17% ± 5% of viable cells were detected among liquid-sampled cells compared to 79% ± 5% or 47% ± 4%, respectively, when the viability was evaluated on the surface after or without the sampling procedure. Moreover, assessments of the survivors collected in the liquid phase, evaluated using the microscopic method and standard plate counts, were well correlated. Evaluations based on the determination of survivors among the liquid-sampled cells can thus overestimate the efficiency of surface disinfection procedures.     

Pro-apoptotic Sorafenib signaling in murine hepatocytes depends on malignancy and is associated with PUMA expression in vitro and in vivo

The multi-kinase inhibitor Sorafenib increases the survival of patients with advanced hepatocellular carcinoma (HCC). Current data suggest that Sorafenib inhibits cellular proliferation and angiogenesis and promotes apoptosis. However, the underlying pro-apoptotic molecular mechanisms are incompletely understood. Here we compared the pro-apoptotic and anti-proliferative properties of Sorafenib in murine hepatoma cells and syngeneic healthy hepatocytes in vitro and in animal models of HCC and liver regeneration in vivo. In vitro, we demonstrate that cell cycle activity and expression of anti-apoptotic Bcl-2 like proteins are similarly downregulated by Sorafenib in Hepa1-6 hepatoma cells and in syngeneic primary hepatocytes. However, Sorafenib-mediated activation of caspase-3 and induction of apoptosis were exclusively found in hepatoma cells, but not in matching primary hepatocytes. We validated these findings in vivo by applying an isograft HCC transplantation model and partial hepatectomy (PH) in C57BL/6 mice. Sorafenib treatment activated caspase-3 and thus apoptosis selectively in small tumor foci that originated from implanted Hepa1-6 cells but not in surrounding healthy hepatocytes. Similarly, Sorafenib did not induce apoptosis after PH. However, Sorafenib treatment transiently inhibited cell cycle progression and resulted in mitotic catastrophe and enhanced non-apoptotic liver injury during regeneration. Importantly, Sorafenib-mediated apoptosis in hepatoma cells was associated with the expression of p53-upregulated-modulator-of-apoptosis (PUMA). In contrast, regenerating livers after PH revealed downregulation of PUMA and were completely protected from Sorafenib-mediated apoptosis. We conclude that Sorafenib induces apoptosis selectively in hepatoma cells but not in healthy hepatocytes and can additionally increase non-apoptotic hepatocyte injury in the regenerating liver.     

Behavioural differences between male and female carpenter bees in nectar robbing and its effect on reproductive success in Glechoma longituba (Lamiaceae)

Male and female nectar robbers may show significantly different behaviour on host plants and thus have different impacts on reproductive fitness of the plants. A 4-year study in natural populations of Glechoma longituba has shown that male carpenter bees (Xylocopa sinensis) are responsible for most of the nectar robbing from these flowers, while female bees account for little nectar robbing, demonstrating distinct behavioural differentiation between male and female bees in visiting flowers. The smaller male bee spends less time visiting a single flower than the larger female bee, consequently, the male bee is capable of visiting more flowers per unit time and has a higher foraging efficiency. Moreover, the robbing behaviour of female carpenter bees is more destructive and affects flower structures (ovules and nectaries) and floral life-span more than that of the male bee. According to the energy trade-off hypothesis, the net energy gain for male bees during nectar robbing greatly surpasses energy payout (17.72 versus 2.43 J), while the female bee net energy gain is barely adequate to meet energy payout per unit time (3.78 versus 2.39 J). The differences in net energy gain for male and female bees per unit time in nectar robbing are the likely cause of observed behavioural differences between the sexes. The differences in food resource preference between male and female bees constitute an optimal resource allocation pattern that enables the visitors to utilise floral resources more efficiently.