Fetal mortality at the time of chorionic villi sampling

Summary To estimate the background fetal loss rates among women who might be candidates for chorionic villi sampling (CVS) for prenatal diagnosis, we examined the frequency of spontaneous abortion and of non-viable fetuses in two groups of women thought to be pregnant at 8–12 weeks' gestation. Among 1519 women over 35 years given an appointment for amniocentesis 1978–1981, 9.8% had a spontaneous abortion prior to 16 weeks' gestation. For those under observation before week 12, the loss rate by 16 weeks was 15.3%. Among all 190 candidates for elective termination of pregnancy between 6 and 12 weeks' gestation, 12.6% were found to have a non-viable fetus at the scheduled date of abortion. The frequency of non-viability was 14% among those seen before week 12. The data suggest that the background loss rate between the time of CVS and the time of amniocentesis is approximately 1–2% and is unlikely to be higher than 9%. Until randomized clinical trials of the procedure are completed we will not know how much, if at all, the loss rate associated with CVS is increased above this background. Nevertheless, knowledge of these background risk estimates may be useful in counseling women considering participating in trials of CVS.     

Comparison of phospho- and dephospho-ATP citrate lyase

The dephospho- form of rat liver citrate lyase has been prepared by treating purified [³²P]-ATP citrate lyase with a partially purified phosphatase. A comparison of the properties of the phospho- and dephosphoenzyme has been performed. The pH optima were the same for both forms of the enzyme in four different buffer systems although the optimum values varied identically for both enzyme forms with the buffer. Both the phospho- and dephosphoenzymes show the same kinetic properties except for the K_m observed for ATP in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer system where it was 54 μm for the phosphoenzyme and 292 μm for the dephosphoenzyme. The present study also indicates that both enzymes are cleaved by trypsin and lysosomal proteases in a similar manner. Both forms of the enzyme tend to associate with mitochondria to the same extent and both enzymes have identical temperature stability curves.     

Immunohistochemical localization of vitamin D-dependent calcium-binding protein in duodenum,kidney, uterus and cerebellum of chickens

Summary Calcium-binding protein (CaBP) has been localized with the immunoperoxidase method using antiserum against purified chick duodenal CaBP. Different preparative procedures were employed to investigate the experimental conditions possibly responsible for the contradictory reports in the literature of the precise cellular localization of CaBP. Freeze substitution, frozen sections followed by fixation and coagulant and non-coagulant fixatives were used with appropriate control sections to demonstrate that the true localization of CaBP in the chick duodenum is in the absorptive cell cytoplasm. The goblet cell localization reported in the literature seems to be a diffusion artifact due to inadequate fixation. CaBP was also localized in several other tissues. In the hen uterus, the tubular glands beneath the surface epithelium showed intense reaction. In the kidney, CaBP was present in the cells of the straight and convoluted segments of distal tubules. The cortex of the chick cerebellum showed the CaBP in Purkinje cells. The entire dendritic trees contained the reaction product. No other neurons in the molecular or the granular layer were stained. In the deep cerebellar nuclei, all neurons were negative and these were outlined by deeply staining axons of the Purkinje cells and their synaptic endings.     

The biology of the marine sponge Microciona prolifera (Ellis and Solander). III. Spicule secretion and the effect of temperature on spicule size

The secretion of siliceous spicules in the marine demosponge Microciona prolifera (Ellis and Solander) is by three different means. Styles are secreted by sclerocytes with archeocyte characteristics (nucleolate nucleus, phagosomes). chelas are formed by small sclerocytes with anucleolate nuclei, and toxas are apparently formed extracellularly within membranous material. Genetically and physiologically equivalent explants of this sponge were grown at 15, 20, and 25 C for four weeks. Analyses of spicule dimensions show little correlation of temperature with spicule length, except in the case of toxas. but a clear inverse relationship of spicule width with temperature. It is suggested that thicker spicules are formed at lower temperatures due to the more efficient entrapment of silicon rather than to effects upon silicon transport. Chela dimensions are very uniform implying an all or none process in their secretion. Differences in spicule dimensions between individual sponges grown at these temperatures may be due to the highly complex pathways of silicon transport and/or to genetic differences.     

Natural enemies ofAcraea terpsicore [Lep.: Nymphalidae] in ghana,with particular reference to the parasiteCharops diversipes [Hym.: Ichneumonidae]

The arthropod parasites and predators ofAcraea terpsicore (L.) were determined in the forest zone of Ghana. An unidentified mite was predatory on the very young larvae. The pentatomidsPlatynopus rostratus Dru. andMacrorhaphis acuta (Dall.) were also predatory on the larvae.Telenomus sp. parasitized the eggs. The tachinidCarcelia normula (Curran) and the ichneumonidCharops diversipes Roman were parasitic on the larvae.C. diversipes was hyperparasitized by the chalcididBrachymeria feae Masi and the eulophidPediobius taylori Kerrich. Laboratory tests showed that parasitism ofA. terpsicore byC. diversipes was significantly highest in the 1st instar, followed by the 2nd, 3rd and 4th. The 5th instar was not parasitized. These results seemed to reflect both host susceptibility and parasite preference. Only a singleC. diversipes larva developed in a host. The developmental period of the parasite egg and larva varied inversely with the age of the host at which it was parasitized. A femaleC. diversipes could oviposit immediately after emergence.     

Schistosoma mansoni: glutathione S-transferase-catalyzed detoxication of dichlorvos

Dialyzed cytosol of adult Schistosoma mansoni worm pairs catalyzed the glutathione-dependent O-demethylation of dichlorvos (2,2-dichlorovinyl dimethylphosphate), the active form of the antischistosomal drug metrifonate, to form a thioether conjugate, S-methylglutathione, and desmethyl dichlorvos. The reaction rate was dependent on both time and protein concentration, and no product was formed when either dichlorvos or glutathione was omitted from the reaction mixture. Female worm cytosols were about 2.5-fold more active per milligram of protein that those of males. Partial purification of glutathione S-transferases from male worms by affinity chromatography on glutathione-agarose showed that the reaction could be catalyzed by a preparation containing the three major isoenzymes, but that the unbound fraction, which contains at least one additional form of the enzyme that is particularly active with epoxide substrates, was 16-fold more active toward dichlorvos than the bound fraction. S-Methylglutathione also was formed by S. mansoni worm pairs incubated in the presence but not in the absence of dichlorvos. Because GSH S-transferase-catalyzed metabolism of dichlorvos results in the formation of desmethyldichlorvos, which unlike the parent compound is not an effective acetylcholinesterase inhibitor, the reaction represents a pathway of detoxication in schistosomes. It is the first example of a clinically used schistosomicide shown to be detoxicated by a conjugation pathway. These results raise the possibility that dichlorvos detoxication by S. mansoni may help explain why this species is normally refractory to metrifonate.     

PHYSIOLOGICAL AND OPTICAL PROPERTIES OF RHIZOSOLENIA FORMOSA (BACILLARIOPHYCEAE) IN THE CONTEXT OF OPEN-OCEAN VERTICAL MIGRATION1

Cultures of Rhizosolenia formosa H. Peragallo were studied to assess whether or not physiological and optical characteristics of this large diatom were consistent with the ability to migrate vertically in the open ocean. Time-course experiments examined changes in chemical composition and buoyancy of R. formosa during nitrate (N)–replete growth, N starvation, and recovery. Cells could maintain unbalanced growth for at least 53 h after depletion of ambient nitrate. Increases in C:N and carbohydrate: protein ratios observed during N starvation reversed within 24 h of reintroduction of nitrate to culture medium. Buoyancy was related to nutrition: Upon N depletion, the percentage of positively buoyant cells decreased to 4% from 11% but reverted to 9% within 12 h of nitrate readdition. Cells took up nitrate in the dark. Nitrogen-specific uptake rates averaged 0.48 d^?1; these rates were higher than N-specific growth rates (0. 15 d^?1), indicating the potential for luxury consumption of nitrate, which can be stored for later use. Measurements of photosynthesis vs. irradiance, chlorophyll-specific absorption (a_ph*(λ)), and pigment composition showed that cells may be adapted for growth under a wide range of irradiances. Values of a_ph*(λ) were lower for N-depleted cells than for N-replete cells, and N-depleted cells had higher ratios of total carotenoids to chlorophyll a. Aggregation of chloroplasts was more pronounced in N-depleted cells. These are possibly photoprotective mechanisms that would be an advantage to N-depleted cells in surface waters. Compounds that absorb in the ultraviolet region were detected in N-replete cells but were absent in N-depleted cultures. Overall, these results have important implications for migrations of Rhizosolenia in nature. Cells may survive fairly long periods in N-depleted surface waters and will continue to take up carbon; then they can resume nitrate uptake and revert to positive buoyancy upon returning to deep, N-rich water. Uncoupled uptake of carbon and nitrogen during migrations of Rhizosolenia is a form of new production that may result in the net removal of carbon from oceanic surface waters.     

Oligosaccharide microarrays for high-throughput detection and specificity assignments of carbohydrate-protein interactions

We describe microarrays of oligosaccharides as neoglycolipids and their robust display on nitrocellulose. The arrays are obtained from glycoproteins, glycolipids, proteoglycans, polysaccharides, whole organs, or from chemically synthesized oligosaccharides. We show that carbohydrate-recognizing proteins single out their ligands not only in arrays of homogeneous oligosaccharides but also in arrays of heterogeneous oligosaccharides. Initial applications have revealed new findings, including: (i) among O-glycans in brain, a relative abundance of the Lewis(x) sequence based on N-acetyllactosamine recognized by anti-L5, and a paucity of the Lewis(x) sequence based on poly-N-acetyllactosamine recognized by anti-SSEA-1; (ii) insights into chondroitin sulfate oligosaccharides recognized by an antiserum and an antibody (CS-56) to chondroitin sulfates; and (iii) binding of the cytokine interferon-gamma (IFN-gamma) and the chemokine RANTES to sulfated sequences such as HNK-1, sulfo-Lewis(x), and sulfo-Lewis(a), in addition to glycosaminoglycans. The approach opens the way for discovering new carbohydrate-recognizing proteins in the proteome and for mapping the repertoire of carbohydrate recognition structures in the glycome.