Effect of insulin on ultrastructure and glycogenesis in primary cultures of adult rat hepatocytes

Insulin in the presence of high concentrations of glucose has a beneficial trophic effect on the development of primary cultures of hepatocytes. Compared to the situation observed in hormone-free control cultures, the flattening of the reaggregated hepatocytes is enhanced, and the reconstituted cell trabeculae are enlarged and tend to form a confluent monolayer after 3 days; the survival time is prolonged from 3 to 5 or 6 days. Ultrastructural modifications are also initiated by insulin; numerous glycogen particles appear after 24 h, in between the cisternae of the proliferated smooth endoplasmic reticulum. After 48 h, large amounts of glycogen are stored, and numerous polysomes are present. A small number of cells showed an increased synthesis of lipid droplets in the lumen of the smooth endoplasmic reticulum and form liposomes at the same time. After 72 h, cytolysomes filled with glycogen develop, simulating glycogenosis type II. Simultaneously, microtubules and microfilaments, closely related to numerous polysomes, appear in cytoplasmic extensions constituting undulating membranes. The biochemical data demonstrate that, in the absence of insulin, a high concentration of glucose stimulates glycogenesis and hinders glycogenolysis. This effect of glucose on polysaccharide synthesis is progressively lost. The addition of insulin to the culture induces after 48 and 72 h, a three- to fivefold increase of the glucose incorporation into glycogen, as compared to the controls. The presence of insulin is required to maintain the hepatocyte's capacity to store glycogen. Glycogen synthetase is converted into its active form under the influence of glucose. Insulin increases the rate of activation.     

Estimation of heterozygosity for single-probe multilocus DNA fingerprints

In spite of the increasing application of DNA fingerprinting to natural populations and to the genetic identification of humans, explicit methods for estimation of basic population genetic parameters from DNA fingerprinting data have not been developed. Contributing to this omission is the inability to determine, for multilocus fingerprinting probes, relatively important genetic information, such as the number of loci, the number of alleles, and the distribution of these alleles into specific loci. One of the most useful genetic parameters that could be derived from such data would be the average heterozygosity, which has traditionally been employed to measure the level of genetic variation within populations and to compare genetic variation among different loci. We derive here explicit formulas for both the estimation of average heterozygosity at multiple hypervariable loci and a maximum value for this estimate. These estimates are based upon the DNA restriction-pattern matrices that are typical for fingerprinting studies of humans and natural populations. For several empirical data sets from our laboratory, estimates of average and maximal heterozygosity are shown to be relatively close to each other. Furthermore, variances of these statistics based on simulation studies are relatively small. These observations, as well as consideration of the effect of missing alleles and alternate numbers of loci, suggest that the average heterozygosity can be accurately estimated using phenotypic DNA fingerprint patterns, because this parameter is relatively insensitive to the lack of certain genetic information.      

Granulocyte-macrophage colony-stimulating factor (GM-CSF) decreases left ventricular function. An echocardiographic study in cancer patients

To study the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the heart, echocardiographic assessments of left ventricular (LV) end-diastolic and end-systolic (ES) diameters (D), ejection fraction (EF) and cardiac output (CO) were done in six male patients (28-70 years of age) with advanced sarcoma (Group 1), prior to (day -1-0), during (day 7-9) and after (day 20-21) a first course of i.v. doxorubicin (day 0) without GM-CSF and a second course (3 weeks after the first one) with GM-CSF 250 microg/m(2)subcutaneously and daily from day 1-11. A similar study was done in ten female patients with advanced breast cancer (31-58 years of age, Group 2) for a first course of doxorubicin+cyclophosphamide with GM-CSF (same schedule as in Group 1). As compared to the mean of values prior to and after the course with GM-CSF in Group 1 and 2, the LVESD during GM-CSF administration transiently increased by median 6% (range -19 to 30%, P<0.05) vs -9% (-21 to 6%, not significant) in the first course without GM-CSF in Group 1 (P<0.05 between courses). The CO and EF tended to decrease during GM-CSF. GM-CSF thus causes a small and transient decrease of LV contractility.     

Experimental evaluation of the relationship between lethal or non-lethal virulence and transmission success in malaria parasite infections

Background

Theoretical studies suggest that direct and indirect selection have the potential to cause substantial evolutionary change in female mate choice. Similarly, sexual selection is considered a strong force in the evolution of male attractiveness and the exaggeration of secondary sexual traits. Few studies have, however, directly tested how female mate choice and male attractiveness respond to selection. Here we report the results of a selection experiment in which we selected directly on female mating preference for attractive males and, independently, on male attractiveness in the guppy, Poecilia reticulata. We measured the direct and correlated responses of female mate choice and male attractiveness to selection and the correlated responses of male ornamental traits, female fecundity and adult male and female survival.

Results

Surprisingly, neither female mate choice nor male attractiveness responded significantly to direct or to indirect selection. Fecundity did differ significantly among lines in a way that suggests a possible sexually-antagonistic cost to male attractiveness.

Conclusions

The opportunity for evolutionary change in female mate choice and male attractiveness may be much smaller than predicted by current theory, and may thus have important consequences for how we understand the evolution of female mate choice and male attractiveness. We discuss a number of factors that may have constrained the response of female choice and male attractiveness to selection, including low heritabilities, low levels of genetic (co)variation in the multivariate direction of selection, sexually-antagonistic constraint on sexual selection and the "environmental covariance hypothesis".

     

An evaluation of the M-statistic in human odontomorphometric distance analyses

The usefulness of the M-statistic in odontomorphometric distance analyses was evaluated against a battery of more traditional metrics, which included Mahalanobis' D², Penrose's shape metric, the Manhattan distance and Delta. Odontometric data used for the analyses were derived from 202 Paraguayan Lengua Indians and 125 contemporary caucasoids. Efron's Bootstrap procedure was used to evaluate the statistical accuracy of the different metrics, when each was applied to the same populations. Additionally, metric stability in the face of reduced sample size, statistical bias resulting from over- and underestimation, and the effects of standardization, were investigated. Our results indicated that Penrose's shape metric rather that the recently introduced M-statistic was the most reliable metric evaluated. Penrose's shape remained the most reliable when sample size was artificially reduced and when raw data were used. Interestingly, Mahalanobis' generalized distance emerged as the least reliable statistics, especially when used on small sample sizes.     

Haptoglobin and CCR2 receptor expression in ovarian cancer cells that were exposed to ascitic fluid: Exploring a new role of haptoglobin in the tumoral microenvironment

Haptoglobin (Hp) is an acute-phase protein that is produced by the liver to capture the iron that is present in the blood circulation, thus avoiding its accumulation in the blood. Moreover, Hp has been detected in a wide variety of tissues, in which it performs various functions. In addition, this protein is considered a potential biomarker in many diseases, such as cancer, including ovarian carcinoma; however, its participation in the cancerous processes has not yet been determined. The objective of this work was to demonstrate the expression of Hp and its receptor CCR2 in the ovarian cancer cells and its possible involvement in the process of cell migration through changes in the rearrangement of the actin cytoskeleton using western blot and wound-healing assays and confirming by confocal microscopy. Ovarian cancer cells express both Hp and its receptor CCR2 but only after exposure to ascitic fluid, inducing moderated cell migration. However, when the cells are exposed to exogenous Hp, the expression of CCR2 is induced together with drastic changes in the actin cytoskeleton rearrangement. At the same time, Hp induced cell migration in a much more efficient manner than did ascitic fluid. These effects were blocked when the CCR2 synthetic antagonist RS102895 was used to pretreat the cells. These results suggest that Hp-induced changes in the cell morphology, actin cytoskeleton structure, and migration ability of tumor cells, is possibly “preparing” these cells for the potential induction of the metastatic phenotype.     

Pennycress double‐cropping does not negatively impact spider diversity

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