Cloning of Choriocarcinoma Cells Shows That Invasion Correlates with Expression and Activation of Gelatinase A

Implantation and placental development are dependent upon trophoblast invasion of the endometrium. While the villous trophoblast does not display invasive behavior, the extravillous cytotrophoblast is highly invasive. By cloning BeWo choriocarcinoma cells, we have isolated two distinct clones that share similarities with villous and extravillous cytotrophoblasts. When cultured at the surface of a type I collagen gel, BeWo MC-1 cells were not invasive, whereas BeWo MC-2 cells rapidly invaded this matrix. When injected subcutaneously in nude mice, BeWo MC-1 cells developed a localized tumor and BeWo MC-2 cells developed larger tumors with micrometastases. Gelatinase A expression and minute amounts of gelatinase B were detected in the parental cell line and in both clones. However, the parental and the BeWo MC-2 cells secreted 5- to 10-fold more gelatinase A than the BeWo MC-1 cells. Laminin and matrigel stimulated the production of gelatinase A in BeWo MC-2 cells. Type I collagen promoted the conversion of the 72-kDa progelatinase A in an active enzyme only in parental BeWo and in BeWo MC-2 cells. These clones provide an interesting model for studying the complex mechanisms regulating implantation as well as the controlled invasiveness during implantation compared to tumor invasion.     

The level of pancreatic PLA2 receptor is closely associated with the proliferative state of rat uterine stromal cells

Rat uterine stromal cells (U_III) express pancreatic type PLA₂ (PLA₂-I) receptor and internalize the enzyme bound to receptors. Here, we investigate the proliferating effect and alterations in binding of PLA₂-I. There is a dramatic decline in PLA₂-I binding in U_III cells as they progress from a nonconfluent proliferating state (40,000 sites/cell) to a confluent state (1300 sites/cell). Intracellular concentration of PLA₂-I changed with the alteration in binding, suggesting that regulation in the PLA₂ binding capacity may have important implications in growth control mechanisms.     

Colonial breeding and speciation in birds

Summary It was recently suggested that bird species which breed colonially might be under stronger sexual selection, have faster rates of evolution and might therefore speciate more rapidly than bird species which do not. If true, then colonial taxa should contain more species than non-colonial taxa, other things being equal. When similarity through common descent is accounted for, there is little evidence for an association between the number of species in a clade and whether it is colonial or not.     

Advantages of the scanning ion microscopy for mapping halogen corticoids in normal and transformed cells in culture

Summary— The intra-cellular distribution of eight halogen glucocorticoids was investigated by ion microscopy in two cellular varieties of cultured non-cancer cells (fibroblast 3T3) and cancer cells (human breast tumor cells MCF-7). Two types of ion microscopy helped to determine this distribution, a direct imaging ion microscope (SMI 300) with low spatial resolution, and a scanning ion microscope (IMS4F), featuring high resolution, serving to obtain maps representing the intra-cellular distribution of the fluorine elements and drugs present in these monolayer cultured cells. The fluorine images representative of the drugs containing fluorine showed that these drugs are essentially concentrated in the cell nuclei. In these nuclei, the distribution of these drugs is different from that of heterochromatin and of the nucleolus.     

SEXUAL SELECTION IN THE BARN SWALLOW (HIRUNDO RUSTICA). IV. PATTERNS OF FLUCTUATING ASYMMETRY AND SELECTION AGAINST ASYMMETRY

The patterns of variation in fluctuating asymmetry were studied in four morphological characters of the barn swallow Hirundo rustica. The level of absolute and relative asymmetry was larger in the secondary sexual character “outer tail length” than in three nonsexual morphological traits (wing, central tail, and tarsus length). The extent of individual asymmetry in outer tail length was negatively correlated with tail-ornament size, whereas the relationship between asymmetry of all other morphological characters and their size was flat or U-shaped. Asymmetry in outer tail length was unrelated to asymmetry in other morphological characters, whereas asymmetries in the length of wing, central tail, and tarsus were positively correlated. Male bam swallows exhibited larger asymmetry in outer tail length than females. Asymmetry of most morphological traits exhibited intermediate repeatabilities between years, with the exception of male and female outer tail length, which were highly repeatable. Tail asymmetry of offspring weakly, though significantly, resembled that of their parents. Asymmetry in wing and outer tail length was also significantly related to several fitness components. Male barn swallows that acquired a mate were less asymmetric in wing and outer tail length than unmated males. Females with more asymmetrical tails laid eggs significantly later. Annual reproductive success was unrelated to fluctuating asymmetry. Male barn swallows that survived were less asymmetric in wing and outer tail length than nonsurvivors, whereas female survivors were less asymmetric in outer tail length than nonsurvivors. These results suggest that levels of fluctuating asymmetry in barn swallows are associated with differences in fitness.     

The role of Mg2+ in the hydrolytic activity of the isolated chloroplast ATPase: Study by high-performance liquid chromatography

The influences of total magnesium ion concentration at different total ATP concentrations, and of total ATP concentration, for different total magnesium ion concentrations, on the enzymatic rate of the isolated chloroplast F₁ ATPase, have been followed by a chromatographic method consisting in the separation and determination of ADP. From the various series of curves, it is concluded that the experimental results (position of the maxima,K _m values) are better fitted by a mechanism involving the activation of the enzyme by magnesium ion and hydrolysis of free ATP, rather than by the classical mechanism, for which the enzyme hydrolyzes the MgATP complex and is inhibited by Mg²⁺. Although the equations giving the reaction rate are similar in the two cases, the calculated values ofK _m are widely different. The value obtained from the classical mechanism does not agree withK _D , the dissociation constant of the enzyme-substrate complex, measured by the Hummel and Dreyer method. Moreover, when the total ATP concentration tends toward the total magnesium ion concentration, the nucleotide binding to the enzyme tends toward zero, although it should be maximum if MgATP were the true substrate. Finally, the inhibitory effect of Na⁺ is more easily explained as a competition between this ion and the activating Mg²⁺, than by the classical mechanism.     

Chromosomal localization of the human histamine H1-receptor gene

We have assigned the human histamine H₁-receptor gene to chromosome 3 by Southern blot analysis of a chromosome mapping panel constructed from humanhamster somatic cell hybrids. This assignment was confirmed by in situ hybridization on metaphase chromosomes and involved bands 3p14–p21.     

Skewed inactivation of an X chromosome deleted at the dystrophin gene in an asymptomatic mother and her affected daughter

A girl with severe Becker muscular dystrophy and apparently normal chromosomes had a heterozygous deletion for exons 51, 52, and 53 of the dystrophin gene. This deletion was transmitted by her mother, who was unaffected. To differentiate the normal and the deleted X chromosomes, fluorescence in situ hybridization (FISH) was applied to metaphase chromosomes, using probes for both exons 51 and 52, which are only 388 and 113 base pairs long, respectively. FISH signals were observed in one or both chromatids of one chromosome, but never on both chromosomes, suggesting the lack of hybridization on the deleted X chromosome. Using 5-bromodeoxyuridine incorporation to differentiate the late (inactive) and the early replicating (active) X chromosomes, 77% of the signals were observed on the active X chromosomes in the mother. This percentage was only 18% in the daughter, suggesting that skewed inactivation of the X chromosomes was responsible for the phenotypic differences.     

Heterogeneous Na+ Sensitivity of Na+,K+-ATPase Isoenzymes in Whole Brain Membranes

Abstract: The Na⁺ sensitivity of whole brain membrane Na⁺,K⁺-ATPase isoenzymes was studied using the differential inhibitory effect of ouabain (α1, low affinity for ouabain; α2, high affinity; and α3, very high affinity). At 100 m M Na⁺, we found that the proportion of isoforms with low, high, and very high ouabain affinity was 21, 38, and 41%, respectively. Using two ouabain concentrations (10⁻⁵ and 10⁻⁷ M ), we were able to discriminate Na⁺ sensitivity of Na⁺, K⁺-ATPase isoenzymes using nonlinear regression. The ouabain low-affinity isoform, α1, exhibited high Na⁺ sensitivity [ K _a of 3.88 ± 0.25 m M Na⁺ and a Hill coefficient ( n ) of 1.98 ± 0.13]; the ouabain high-affinity isoform, α2, had two Na⁺ sensitivities, a high ( K _a of 4.98 ± 0.2 m M Na⁺ and n of 1.34 ± 0.10) and a low ( K _a of 28 ± 0.5 m M Na⁺ and an n of 1.92 ± 0.18) Na⁺ sensitivity activated above a thresh old (22 ± 0.3 m M Na⁺); and the ouabain very-high-affinity isoform, α3, was resolved by two processes and appears to have two Na⁺ sensitivities (apparent K _a values of 3.5 and 20 m M Na⁺). We show that Na⁺ dependence in the absence of ouabain is the result of at least of five Na⁺ reactivities. This molecular functional characteristic of isoenzymes in membranes could explain the diversity of physiological roles attributed to isoenzymes.     

Patterns of fluctuating asymmetry in sexual ornaments predict female choice

Extravagant secondary sexual characters are assumed to have arisen and be maintained by sexual selection. While traits like horns, antlers and spurs can be ascribed to intrasexual competition, other traits such as extravagant feather ornaments, displays and pheromones have to be ascribed to mate choice. A number of studies have tested whether females exert selection on the size of male ornaments, but only some of these have recorded female preferences for the most extravagantly ornamented males. Here I demonstrate that female choice can be directly predicted from the relationship between the degree of fluctuating asymmetry and the size of a secondary sexual character. Fluctuating asymmetry is an epigenetic measure of the ability of individuals to cope with stress, and it occurs when an individual is unable to undergo identical development of an otherwise bilaterally symmetric trait on both sides of its body. There is a negative relationship between the degree of fluctuating asymmetry and the absolute size of an ornament in those bird species with a female preference for the largest male sex trait, while there is a flat or U-shaped relationship among species without a female preference. These results suggest that females prefer exaggerated secondary sexual characters if they reliably demonstrate the ability of males to cope with genetic and environmental stress. Some species may demonstrate a flat or U-shaped relationship between the degree of fluctuating asymmetry and the absolute size of an ornament because (i) the genetic variance in viability signalled by the secondary sex trait has been depleted; (ii) the secondary sex trait is not particularly costly and therefore does not demonstrate condition dependence; or because (iii) the sex traits can be considered arbitrary traits rather than characters reflecting good genes.